Editing Underwater archaeology

{{Short description|Study of human activity via evidence found underwater}}
[[File:Scale drawing underwater.jpg|thumb|Drawing to scale, underwater]]
[[File:LakeMurray rockhouse overview.jpg|thumb|Rock house settlement seen on left in 1927 while [[Lake Murray (South Carolina)]] was under construction, middle and right are two angles of aspect on [[Side-scan sonar]] in 100 ft of fresh water under the lake in 2005]]
[[File:Kaubalaeva "E. Russ" vrakk.jpg|thumb|The wreck of ''E. Russ'' in [[Estonia]] is considered a [[National heritage site|national heritage monument]].]]
'''Underwater archaeology''' is [[archaeology]] practiced [[underwater]].<ref name="Mar Arch" >{{cite web|title=Underwater and Maritime Archeology in Latin America and the Caribbean|page=21 }}</ref> As with all other branches of archaeology, it evolved from its roots in pre-history and in the [[classical era]] to include sites from the historical and industrial eras. 

Its acceptance has been a relatively late development due to the difficulties of accessing and working underwater sites, and because the application of archaeology to underwater sites initially emerged from the skills and tools developed by shipwreck salvagers.<ref name="Akesson">{{cite web |url=http://www.abc.se/~pa/uwa/history.htm |title=A history of underwater archaeology |first=Per |last=Akesson |work=Nordic Underwater Archaeology |access-date=2005-10-01 |archive-date=2018-12-09 |archive-url=https://web.archive.org/web/20181209123738/https://www.abc.se/~pa/uwa/history.htm |url-status=dead }}</ref> As a result, underwater archaeology initially struggled to establish itself as actual archaeological research.<ref name="Gibbins 2001">{{cite journal |last1=Gibbins |first1=David |name-list-style=amp |last2=Adams |first2=Jonathan |title=Shipwrecks and maritime archaeology |journal=World Archaeology |volume=32 |issue=3 |pages=279–291 |year=2001 |doi=10.1080/00438240120048635|s2cid=37301382 }}</ref> This changed when universities began teaching the subject and a theoretical and practical base for the sub-discipline was firmly established in the late 1980s. 

Underwater archaeology now has a number of branches including, [[maritime archaeology]]: the scientifically based study of past [[human]] life, behaviors and cultures and their activities in, on, around and (lately) under the sea, estuaries and rivers.<ref>{{Cite web|date=2019-08-02|title=How underwater archaeology reveals hidden wonders|url=https://www.nationalgeographic.com/culture/archaeology/underwater-archaeology/|archive-url=https://web.archive.org/web/20190802190505/https://www.nationalgeographic.com/culture/archaeology/underwater-archaeology/|url-status=dead|archive-date=August 2, 2019|access-date=2020-09-16|website=Culture|language=en}}</ref> This is most often effected using the physical remains found in, around or under [[Sea water|salt]] or [[fresh water]] or buried beneath water-logged [[sediment]].<ref name="Muckelroy">{{cite book |last=Muckelroy |first=K. |title=Maritime archaeology |publisher=Cambridge University Press |year=1978 |isbn=978-0-521-29348-8}}</ref> In recent years, the study of submerged [[World War II|WWII]] sites and of submerged aircraft in the form of underwater [[aviation archaeology]] have also emerged as bona fide activity.<ref>{{cite web|title=Broken Wings|url=http://museum.wa.gov.au/research/research-areas/maritime-archaeology/treasures-from-the-deep/broken-wings|website=[[Western Australian Museum]]|publisher=[[Government of Western Australia]]|access-date=5 June 2015}}</ref>

Though often mistaken as such, underwater archaeology is not restricted to the study of [[shipwreck]]s. Changes in [[sea-level|sea level]] because of local [[seismic]] events such as the earthquakes that devastated [[Port Royal]] and [[Alexandria]] or more widespread [[climatic]] changes on a [[continent]]al scale mean that some sites of human occupation that were once on dry land are now submerged.<ref name="PortRoyal">{{cite web|url=http://nautarch.tamu.edu/portroyal/|title=Port Royal Project: Home}}</ref><ref name="BouldnerCliff">{{cite web|url=http://www.soton.ac.uk/mediacentre/news/2007/jul/07_90.shtml|title=:: University of Southampton|author=University of Southampton|url-status=dead|archive-url=https://web.archive.org/web/20070819063330/http://www.soton.ac.uk/mediacentre/news/2007/jul/07_90.shtml|archive-date=19 August 2007}}</ref> At the end of the last ice age, the [[North Sea]] was a great plain, and [[Anthropology|anthropological]] material, as well as the remains of animals such as [[mammoths]], are sometimes recovered by trawlers. Also, because human societies have always made use of water, sometimes the remains of structures that these societies built underwater still exist (such as the foundations of [[crannogs]],<ref name="crannog">{{cite web|url=http://www.crannog.co.uk/|title=The Scottish Crannog Centre}}</ref> [[Bridge|bridges]] and [[Harbor|harbors]]) when traces on dry land have been lost. As a result, underwater [[archaeological]] sites cover a vast range including: submerged indigenous sites and places where people once lived or visited that have been subsequently covered by water due to rising [[sea level]]s; wells, [[cenote]]s, wrecks ([[shipwrecks]]; [[aircraft]]); the remains of structures created in water (such as crannogs, bridges or harbors); other port-related structures; [[refuse]] or [[debris]] sites where people disposed of their [[waste]], garbage and other items, such as ships, aircraft, munitions and machinery, by [[ocean dumping|dumping]] into the water.

Underwater archaeology is often complementary to archaeological research on terrestrial sites because the two are often linked by many and various elements including geographic, social, political, economic and other considerations. As a result, a study of an archaeological landscape can involve a multidisciplinary approach requiring the inclusion of many specialists from a variety of disciplines including [[prehistory]], [[historical archaeology]], [[maritime archaeology]], and [[anthropology]]. There are many examples. One is the wreck of the VOC ship ''[[Zuytdorp]]'' lost in 1711 on the coast of Western Australia, where there remains considerable speculation that some of the crew survived and, after establishing themselves on shore, intermixed with indigenous tribes from the area.<ref>{{cite web |url=http://www.museum.wa.gov.au/maritime-archaeology-db/wrecks/id-811 |publisher=Shipwreck Databases Western Australian Museum |title= Zuiddorp (Zuytdorp) (1712/06) North of Kalbarri}}</ref>  The archaeological signature at this site also now extends into the interaction between indigenous people and the European [[Pastoralism|pastoralists]] who entered the area in the mid-19th century.<ref>{{cite web |url=http://www.mm.wa.gov.au/Museum/march/shipwrecks/Zuytdorp/Zuytdorp.html |title=The Zuytdorp Story table of contents |access-date=11 November 2010 |url-status=dead |archive-url=https://web.archive.org/web/20040603062706/http://www.mm.wa.gov.au/Museum/march/shipwrecks/Zuytdorp/Zuytdorp.html |archive-date=3 June 2004}}</ref>

== Research potential ==
There are many reasons why underwater archaeology can make a significant contribution to our knowledge of the past. In the shipwreck field alone, individual [[shipwreck]]s can be of significant historical importance either because of the magnitude of loss of life (such as the [[RMS Titanic|''Titanic'']]) or circumstances of loss (''[[USS Housatonic (1861)|Housatonic]]'' was the first vessel in history sunk by an enemy submarine).<ref name="Titanic">{{cite web|url=http://www.titanicinquiry.org/|title=TIP – United States Senate Inquiry|access-date=2007-12-18|archive-url=https://web.archive.org/web/20071213181241/http://www.titanicinquiry.org/|archive-date=2007-12-13|url-status=dead}}</ref><ref name=Housatonic>{{cite web|title=Housatonic i|url=https://www.history.navy.mil/research/histories/ship-histories/danfs/h/housatonic-i.html|publisher=[[Naval History and Heritage Command]]|access-date=5 June 2015|date=15 January 2015}}</ref> Shipwrecks such as ''[[Mary Rose]]'' can also be important for archaeology because they can form a kind of accidental [[time capsule]], preserving an assemblage of human [[Artifact (archaeology)|artifacts]] at the moment in time when the ship was lost.<ref>{{cite web|url=http://www.bbc.co.uk/worldservice/documentaries/2008/08/080821_what_lies_beneath.shtml|title=BBC World Service – Documentaries – What Lies Beneath}}</ref><ref name="Maryrose">{{cite web|url=http://www.maryrose.org/|title=The Mary Rose}}</ref>

Sometimes it is not the wrecking of the ship that is important, but the fact that we have access to the remains of it, especially where the vessel was of major importance and significance in the history of science and engineering (or warfare), due to being the first of its type of vessel. The development of submarines, for example, can be traced via underwater archaeological research, via the ''[[H. L. Hunley (submarine)|Hunley]]'', which was the first submarine to sink an enemy ship (''Hunley'' also had unique construction details not found in previous vessels and was one of the few historic warships ever raised intact);<ref name="Housatonic" /> the [[Resurgam|''Resurgam'' ''II'']], the first powered submarine;<ref name=ACHW2005>{{cite web|title=Advisory Committee on Historic Wreck Sites Annual Report 2005 |url=http://www.english-heritage.org.uk/upload/pdf/ACHWS_annual_report_2005.pdf |publisher=[[Department for Digital, Culture, Media and Sport]] |access-date=5 June 2015 |date=June 2006 |url-status=dead |archive-url=https://web.archive.org/web/20070114115741/http://www.english-heritage.org.uk/upload/pdf/ACHWS_annual_report_2005.pdf |archive-date=14 January 2007 }}</ref> and ''[[Holland 5]]'', which provides insight into the development of submarines in the British Navy.<ref name=DCMS>{{cite web|title=Heritage Minister Andrew McIntosh Acts To Protect Wreck Site Of Prototype Submarine|url=http://www.culture.gov.uk/Reference_library/Press_notices/archive_2005/dcms001_05.htm|publisher=[[Department for Digital, Culture, Media and Sport]]|access-date=5 June 2015|archive-url=http://webarchive.nationalarchives.gov.uk/20060926083354/http://www.culture.gov.uk/Reference_library/Press_notices/archive_2005/dcms001_05.htm|archive-date=26 September 2006|date=4 January 2005}}</ref>

== UNESCO Convention ==
All traces of human existence underwater which are one hundred years old or more are protected by the [[UNESCO Convention on the Protection of the Underwater Cultural Heritage]]. This convention aims at preventing the destruction or loss of historic and cultural information and [[Archaeological looting|looting]]. It helps states parties to protect their underwater cultural heritage with an international legal framework.<ref>UNESCO, Convention on the protection of the Underwater Cultural Heritage [http://www.unesco.org/new/en/culture/themes/underwater-cultural-heritage/]</ref>
On the basis of the recommendations defined in the above-mentioned UNESCO Convention various European projects have been funded such as the CoMAS project<ref>{{cite web |url=http://www.comasproject.eu/index.php?lang=en |title=CoMAS project |archive-url=https://web.archive.org/web/20160919052158/http://www.comasproject.eu/index.php?lang=en |archive-date=19 September 2016 |access-date=24 January 2018}}</ref>
for [[in situ]] conservation planning of underwater archaeological artefacts.<ref>{{cite journal|title=Underwater Power Tools for In Situ Preservation, Cleaning and Consolidation of Submerged Archaeological Remains|journal=Journal of Marine Science and Engineering|date=2021|doi=10.3390/jmse9060676|doi-access=free|last1=Scalercio|first1=Emiliano|last2=Sangiovanni|first2=Francesco|last3=Gallo|first3=Alessandro|last4=Barbieri|first4=Loris|volume=9|issue=6|page=676|bibcode=2021JMSE....9..676S }}</ref><ref>{{cite conference
| title =Electromechanical devices for supporting the restoration of underwater archaeological artefacts
| conference =MTS/IEEE OCEANS 2015 - Genova: Discovering Sustainable Ocean Energy for a New World
| doi =10.1109/OCEANS-Genova.2015.7271597
}}</ref>*{{cite conference |title=A ROV for supporting the planned maintenance in underwater archaeological sites |conference=MTS/IEEE OCEANS 2015 - |location=Genova: Discovering Sustainable Ocean Energy for a New World |doi=10.1109/OCEANS-Genova.2015.7271602 |first1=F. |last1=Bruno |first2=M. |last2=Muzzupappa |first3=A. |last3=Lagudi |first4=A. |last4=Gallo |first5=F. |last5=Spadafora|first6=G. |last6=Ritacco  |first7=A.|last7=Angilica |first8=L. |last8=Barbieri |first9=N. |last9=Di Lecce |first10=G. |last10=Saviozzi |first11=C. |last11=Laschi |first12=R. |last12=Guida |first13=G. |last13=Di Stefano |date= 2015 |pages=1–7 }}

== Challenges ==
Underwater sites are inevitably difficult to access, and more hazardous, compared with working on dry land. In order to access the site directly, [[diving equipment]] and [[Diver training|diving skills]] are necessary. The depths that can be [[scuba diving|accessed by divers]], and the length of time available at depths, are limited. For deep sites beyond the reach of divers, [[submersibles]] or [[remote sensing]] equipment are needed.

For a marine site, while some form of working platform (typically a [[boat]] or [[ship]]) is often needed, shore-based activities are common. Notwithstanding, underwater archaeology is a field plagued by [[logistics]] problems. A working platform for underwater archaeology needs to be equipped to provide for the delivery of air for example, recompression and medical facilities, or specialist remote sensing equipment, analysis of archaeological results, support for activities being undertaken in the water, storage of supplies, facilities for conservation for any items recovered from the water, as well as accommodation for workers. Equipment used for archaeological investigation, including [[water dredge]] and [[Airlift (dredging device)|airlifts]] create additional [[hazard]]s and logistics issues. Moreover, marine sites may be subject to strong [[Tide|tidal]] flows or poor weather which mean that the site is only accessible for a limited amount of time. Some marine creatures also pose a threat to diver safety.

Underwater sites are often dynamic, that is they are subject to movement by [[Ocean current|currents]], [[Ocean surface wave|surf]], [[storm]] damage or tidal flows. Structures may be unexpectedly uncovered, or buried beneath [[sediment]]s. Over time, exposed structures will be eroded, broken up and scattered. The dynamic nature of the environment may make [[in-situ conservation]] infeasible, especially as exposed organics, such as the wood of a shipwreck, are likely to be consumed by marine organisms such as [[Pholadidae|piddocks]]. In addition, underwater sites can be chemically active, with the result that iron can be leached from metal structures to form [[concretions]]. The original metal will then be left in a fragile state. [[Artifact (archaeology)|Artifacts]] recovered from underwater sites need special care.

[[Visibility]] may be poor, because of sediments or [[algae]] in the water and lack of light penetration.<ref name="Cantelas1997">{{cite journal |first1=FJ |last1=Cantelas |first2=BA |last2=Rodgers |title=Tools, Techniques, and Zero Visibility Archaeology. |journal=In: EJ Maney, Jr and CH Ellis, Jr (Eds.) Diving for Science...1997. |volume=Proceedings of the American Academy of Underwater Sciences |issue=17th Annual Scientific Diving Symposium |year=1997 |url=http://archive.rubicon-foundation.org/4636 |access-date=20 October 2010 |archive-url=https://web.archive.org/web/20090403061427/http://archive.rubicon-foundation.org/4636 |archive-date=3 April 2009 |url-status=usurped }}</ref> This means that survey techniques that work well on land (such as triangulation), generally can not be used effectively under water.

In addition it can be difficult to allow access to the results of the archaeological research as underwater sites do not provide good [[outreach]] possibilities or access for the general public.<ref>{{cite web|title=Deepwater Archaeology in Oil and Gas – By Kimberly L. Faulk|url=https://muablog.wordpress.com/2010/12/14/deepwater-archaeology-in-oil-and-gas-by-kimberly-l-faulk-nee-eslinger/|website=Museum of Underwater Archaeology|date=14 December 2010}}</ref> Work has been done to bridge this difficulty through the use of the [[World Wide Web]] for [[webcasting]] projects, or dedicated virtual reality systems <ref>{{cite journal |title=Enhancing learning and access to Underwater Cultural Heritage through digital technologies: the case study of the "Cala Minnola" shipwreck site |journal=Digital Applications in Archaeology and Cultural Heritage |volume=13 |pages=e00103 |date=2019 |doi=10.1016/j.daach.2019.e00103 |last1=Bruno |first1=F. |last2=Barbieri |first2=L. |last3=Muzzupappa |first3=M. |last4=Tusa |first4=S. |last5=Fresina |first5=A. |last6=Oliveri |first6=F. |last7=Lagudi |first7=A. |last8=Cozza |first8=A. |last9=Peluso |first9=R. |s2cid=155526789 }}</ref> that allow users to perform a virtual diving into an interactive 3D reconstruction of the underwater archaeological site. An example is the excavation of the ''[[Queen Anne's Revenge]]''<ref>{{cite journal |first1=C |last1=Southerly |first2=J |last2=Gillman-Bryan |title=Diving on the Queen Anne's Revenge |journal=In: SF Norton (Ed). Diving for Science...2003. |volume=Proceedings of the American Academy of Underwater Sciences |issue=22nd Annual Scientific Diving Symposium |year=2003 |url=http://archive.rubicon-foundation.org/4760 |access-date=20 October 2010 |archive-url=https://web.archive.org/web/20090219004153/http://archive.rubicon-foundation.org/4760 |archive-date=19 February 2009 |url-status=usurped }}</ref> and the ''QAR DiveLive'' program,<ref name="auto">{{cite web|url=http://digital.ncdcr.gov/cdm/ref/collection/p249901coll22/id/695248|title=Live from Morehead City, it's Queen Anne's Revenge|work=ncdcr.gov}}</ref> a live interactive virtual field trip to the wrecksite.

== Techniques ==
<!--target for redirect from [[Underwater archaeology techniques]]-->
Although specialized techniques and tools have been developed to address the challenges of working under water, the archaeological goals and process are essentially the same as in any other context. Investigating an underwater site however, is likely to take longer and be more costly than an equivalent terrestrial one.<ref name="Muckelroy" />

An important aspect of project design is likely to be managing the [[logistics]] of operating from a boat and of managing [[diving operation]]s. The depth of water over the site, and whether access is constrained by tides, currents and adverse weather conditions will create substantial constraints on the techniques that can feasibly be used and the amount of investigation that can be carried out for a given cost or in a set timescale. Many of the most carefully investigated sites, including the ''Mary Rose'' have relied substantially on avocational archaeologists working over a considerable period of time.<ref name="Maryrose" />

As with archaeology on land, some techniques are essentially manual, using simple equipment (generally relying on the efforts of one or more scuba divers), while others use advanced technology and more complex logistics (for example requiring a large support vessel, with equipment handling cranes, underwater communication and computer visualization).

=== Position fixing ===
Knowing the location of an archaeological site is fundamental to being able to study it. In the open sea there are no landmarks, so [[position fixing]] is generally achieved using [[GPS]]. Historically, sites within sight of the shore would have been located using [[Navigational transit|transects]]. A site may also be located by visually [[Position fixing|surveying]] some form of marker (such as a [[buoy]]) from two known (mapped) points on land. The depth of water at a site can be determined from charts or by using the depth sounding [[sonar]] equipment that is standard equipment on ships. Such sonar can often be used to locate an upstanding structure, such as a shipwreck, once GPS has placed the research vessel in approximately the right location.

=== Site survey ===
[[File:Laevavrakk "Aid".png|thumb|[[Side-scan sonar]] image of shipwreck ''Aid'' in [[Estonia]].]]
The type of [[underwater survey|survey]] required depends on the information that is needed to resolve archaeological questions, but most sites will need at least some form of topographical survey and a site plan showing the locations of artifacts and other archaeological material, where samples were taken and where different types of archaeological investigation were carried out. Environmental assessment of archaeological sites will also require that environmental conditions (water chemistry, dynamic properties) as well as the natural organisms present on the site are recorded. For shipwrecks, particularly post-industrial age shipwrecks, pollution threats from wreck material may need to be investigated and recorded.

The simplest approach to survey is to carry out three-dimensional [[surveying]] by divers using [[depth gauge]]s and [[tape measure]]ments.<ref name="3H">{{cite web |url=http://www.threeh.demon.co.uk/ |title=3D survey resource site from 3H |archive-url=https://web.archive.org/web/20060210160101/http://www.threeh.demon.co.uk/ |archive-date=10 February 2006 |access-date=24 January 2018}}</ref> Research shows that such measurements are typically less accurate than similar surveys on land.<ref name="3Htapeerrors">{{cite web |url=http://www.threeh.demon.co.uk/Downloads/Tape%20Accuracy%20Paper.pdf |title=Research on the accuracy of tape survey methods from 3H |archive-url=https://web.archive.org/web/20060601204853/http://www.threeh.demon.co.uk/Downloads/Tape%20Accuracy%20Paper.pdf |archive-date=1 June 2006 |access-date=24 January 2018 |last=Holt |first=Peter }}</ref> Where it is not practical or safe for divers to physically visit a site, [[Remotely Operated Vehicle]]s (ROVs) enable observation and intervention with control by personnel located at the surface.<ref name=NOAAROV>{{cite web|title="ROV" stands for remotely operated vehicle|url=http://oceanexplorer.noaa.gov/facts/rov.html|website=Ocean Explorer|publisher=[[Office of Ocean Exploration]]|access-date=5 June 2015}}</ref> The low technology approach of measuring using tape measures and depth gauges can be replaced with a more accurate and quicker high technology approach using acoustic positioning.<ref name="Wessexacoustic">{{cite web|url=http://www.wessexarch.co.uk/projects/marine/alsf/wrecks_seabed/round2/acoustic-positioning.html|title=The Acoustic Tracking System}}</ref> ROV technology was used during the ''Mardi Gras'' Shipwreck Project. The "Mardi Gras Shipwreck" sank some 200 years ago about 35 miles off the coast of [[Louisiana]] in the [[Gulf of Mexico]] in {{convert|4,000|ft|m|abbr=off|sp=us}} of water.<ref name="Mystery Mardi Gras Shipwreck">{{cite web|title=Mystery Mardi Gras Shipwreck|url=http://nautilusproductions.com/projects/mystery-mardi-gras-shipwreck-documentary|website=Nautilus Productions|access-date=2015-04-10|archive-url=https://web.archive.org/web/20150613054648/http://nautilusproductions.com/projects/mystery-mardi-gras-shipwreck-documentary|archive-date=2015-06-13|url-status=dead}}</ref>

[[Remote sensing]] or Marine Geophysics<ref name="WessexGeophysics">{{cite web|url=http://www.wessexarch.co.uk/projects/marine/alsf/wrecks_seabed/geophysical_survey_methodology.html|title=Geophysical Survey Methodology}}</ref> is generally carried out using equipment towed from a vessel on the surface and therefore does not require any one, or any equipment to actually penetrate to the full depth of the site. Sensitive [[sonar]], especially [[side-scan sonar]] or multi-beam sonar<ref name="Wessexmultibeam">[http://www.wessexarch.co.uk/projects/marine/alsf/wrecks_seabed/multibeam_sonar.html Multibeam sonar evaluated by Wessex Archaeology] as part of ALSF funded "Wrecks on the Seabed" project</ref> may be used to image an underwater site.  [[Magnetometer|Magnetometry]]<ref name="Wessexmagnetometry">[http://www.wessexarch.co.uk/projects/marine/alsf/wrecks_seabed/magnetometer.html Magnetometry evaluated by Wessex Archaeology] as part of ALSF funded "Wrecks on the Seabed" project</ref> can be used to locate metal remains such as metal [[shipwrecks]], [[anchors]] and [[cannon]]. Sub-bottom profiling<ref name="Wessexsubbottom">[http://www.wessexarch.co.uk/projects/marine/alsf/wrecks_seabed/sub_bottom_profiler.html Sub-bottom profiling sonar evaluated by Wessex Archaeology] as part of ALSF funded "Wrecks on the Seabed" project</ref><ref name="Gracedieu">[http://eprints.soton.ac.uk/39914/01/pdf_paper.pdf Sub-bottom profile investigation of the ''Grace Dieu'' from The University of Southampton]</ref> utilizes sonar to detect structures buried beneath sediment.

=== Recording ===
[[File:Diver&shipsbell.jpg|thumb|LAMP archaeologist recording a scaled drawing of the ship's bell discovered on the late 18th century "Storm Wreck" off St. Augustine, Florida]]
A variety of techniques are available to divers to record findings underwater. [[Scale drawing]] is the basic tool of archaeology and can be undertaken underwater. Pencils will write underwater on permatrace, plastic [[Slate (writing)|dive slates]], or matt [[laminated]] paper.

[[Photography]] and [[videography]] are the mainstays of recording, which has become much more convenient with the advent of reasonably priced digital still and HD video cameras. [[Cameras]], including [[video cameras]] can be provided with special underwater housings that enable them to be used for [[underwater videography]]. Low visibility underwater and distortion of image due to refraction mean that perspective photographs can be difficult to obtain. However, it is possible to take a series of photographs at adjacent points and then combined into a single [[Photomontage|photomontage or photomosaic]] image of the whole site. 3D [[photogrammetry]] has also become a very popular way to image underwater cultural materials and shipwreck sites.<ref>{{cite journal |last=Van Damme |first=T |title=Computer Vision Photogrammetry for Underwater Archaeological Site Recording in a Low-Visibility Environment |url=http://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XL-5-W5/231/2015/isprsarchives-XL-5-W5-231-2015.pdf |journal=ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences |volume=XL55 |pages=231–238 |doi=10.5194/isprsarchives-XL-5-W5-231-2015 |bibcode=2015ISPArXL55..231V |access-date=24 April 2016|year=2015 |doi-access=free }}</ref><ref>{{cite journal |last=S.Tusa|title=Enhancing learning and access to Underwater Cultural Heritage through digital technologies: the case study of the "Cala Minnola" shipwreck site|journal=Digital Applications in Archaeology and Cultural Heritage|date=2019|volume=13|pages=e00103|doi=10.1016/j.daach.2019.e00103|s2cid=155526789|url=https://doi.org/10.1016/j.daach.2019.e00103}}</ref>

=== Excavation ===
Where intrusive underwater excavation is appropriate, silts and sediments can be removed from an area of investigation using a [[water dredge]] or [[airlift (dredging device)|airlift]]. When used correctly, these devices have an additional benefit in tending to improve the visibility in the immediate vicinity of the investigation. For very deep sea excavation manned and unmanned submersibles  are sometimes used to view sites. Underwater photography and sonar imaging can also be conducted from these platforms which assists the recording process.

=== Archaeological science ===
A variety of [[archaeological science]]s are used in underwater archaeology. [[Dendrochronology]] is an important technique especially for dating the timbers of wooden ships. It may also provide additional information, including the area where the timber was harvested (i.e. likely to be where the ship was built) and whether or not there are later repairs or reuse of salvaged materials. Because plant and animal material can be preserved underwater, [[archaeobotany]] and [[archaeozoology]] have roles in underwater archaeology. For example, for submerged terrestrial sites or inland water, identification of [[pollen]] samples from sedimentary or silt layers can provide information on the plants growing on surrounding land and hence on the nature of the landscape. Information about metal artifacts can be obtained through [[X-ray]] of concretions. [[Geology]] can provide insight into how the site evolved, including changes in sea-level, [[erosion]] by rivers and [[Deposition (sediment)|deposition]] by rivers or in the sea.

=== Artifact recovery and conservation ===
[[Artifact (archaeology)|Artifacts]] recovered from underwater sites need stabilization to manage the process of removal of water and conservation.<ref name="denix">{{cite book |last=Hamilton |first=Donny L. |title=Basic Methods of Conserving Underwater Archaeological Material Culture |url=http://www.denix.osd.mil/cr/cultural-resources-program-management/archaeology/uploads/basic-methods-of-conserving-underwater-archaeological-material-culture-report-legacy/ |year=1997 |publisher=[[Texas A&M University]] |location=Washington D. C. |access-date=2017-12-01 |archive-url=https://web.archive.org/web/20171202052819/http://www.denix.osd.mil/cr/cultural-resources-program-management/archaeology/uploads/basic-methods-of-conserving-underwater-archaeological-material-culture-report-legacy/ |archive-date=2017-12-02 |url-status=dead }}</ref><ref name=oregonstate>{{cite web|last1=Veilleux|first1=Carol A.|title=Conservation Methods Of Underwater Artifacts|url=http://oregonstate.edu/~veilleuc/UnderwaterArch/UnderwaterArch.htm|publisher=[[Oregon State University]]|access-date=5 June 2015|archive-url=https://web.archive.org/web/20040502121500/http://oregonstate.edu/~veilleuc/UnderwaterArch/UnderwaterArch.htm|archive-date=2 May 2004}}</ref> The artifact either needs to be dried carefully, or the water replaced with some inert medium (as in the case of [[The Mary Rose]]). Artifacts recovered from [[sea water|salt water]], particularly [[metals]] and [[glass]] need be stabilized following absorption of salt or leaching of metals. [[In situ conservation (archaeology)|In-situ conservation]] of underwater structures is possible, but consideration needs to be given to the dynamic nature of the site. Changes to the site during intrusive investigation or removal of artifacts may result in scouring which exposes the site to further deterioration.

=== Interpretation and presentation of underwater archaeology ===
Diver trails also called wreck trails can be used to allow scuba-divers to visit and understand archaeological sites that are suitable for scuba-diving<ref>e.g. Souter, C., 2006 Cultural Tourism and Diver Education. In Maritime Archaeology: Australian Approaches. The Springer Series in Underwater Archaeology. Staniforth, M. & Nash, M. (eds) Springer, New York.</ref> One excellent example is the [[Florida Public Archaeology Network]]'s (FPAN) "Florida Panhandle Shipwreck Trail."<ref>{{cite web|title=Florida Panhandle Shipwreck Trail|url=http://www.floridapanhandledivetrail.com/|website=Florida Panhandle Dive Trail}}</ref> The Florida Panhandle Shipwreck Trail features 12 [[shipwrecks]] including [[artificial reefs]] and a variety of sea life for diving, snorkeling and fishing offshore of Pensacola, Destin, Panama City and Port St. Joe, [[Florida]].<ref>{{cite web|last1=Blair|first1=Kimberly|title=Florida Panhandle Shipwreck Trail beckons divers|url=https://www.usatoday.com/story/travel/2014/08/07/florida-panhandle-shipwreck-trail/13751693/|website=usatoday.com|access-date=17 August 2015}}</ref> Otherwise presentation will typically rely on publication (book or [[academic journal|journal]] articles, web-sites and electronic media such as CD-ROM). Television programs, web videos and social media can also bring an understanding of underwater archaeology to a broad audience. The ''Mardi Gras'' Shipwreck Project<ref>{{cite web|title=Mardi Gras Shipwreck|url=http://uwf.edu/jkent/fpan_preCMS/mardigras/|website=uwf.edu|url-status=dead|archive-url=https://web.archive.org/web/20150516045935/http://uwf.edu/jkent/fpan_preCMS/mardigras/|archive-date=16 May 2015}}</ref> integrated a one-hour HD documentary,<ref name="Mystery Mardi Gras Shipwreck"/> short videos for public viewing and video updates during the expedition as part of the educational outreach. Webcasting is also another tool for educational outreach. For one week in 2000 and 2001, live [[Underwater videography|underwater video]] of the ''[[Queen Anne's Revenge]]'' Shipwreck Project was [[webcast]] to the [[Internet]] as a part of the ''QAR DiveLive''<ref name="auto"/> educational program that reached thousands of children around the world.<ref>{{cite journal |author=C Southerly and J Gillman-Bryan. |title=Diving on the Queen Anne's Revenge |journal=In: SF Norton (Ed). Diving for Science...2003. |volume=Proceedings of the American Academy of Underwater Sciences |issue=22nd Annual Scientific Diving Symposium |year=2003 |url=http://archive.rubicon-foundation.org/4760 |access-date=3 July 2008 |archive-url=https://web.archive.org/web/20090219004153/http://archive.rubicon-foundation.org/4760 |archive-date=19 February 2009 |url-status=usurped }}</ref> Created and co-produced by [[Nautilus Productions]] and Marine Grafics, this project enabled students to talk to scientists and learn about methods and technologies utilized by the underwater archaeology team.<ref>{{cite news|title=Apple, QuickTime help with underwater diving trip|url=http://www.macworld.com/article/1019428/quicktime.html|agency=Macworld}}</ref><ref>{{cite news|title=Blackbeard's Glowing Shipwreck|url=http://www.p3update.com/events/67-lighting/blackbeard-s-glowing-shipwreck|agency=P3 Update|access-date=2015-05-13|archive-url=https://web.archive.org/web/20150402173605/http://www.p3update.com/events/67-lighting/blackbeard-s-glowing-shipwreck|archive-date=2015-04-02|url-status=dead}}</ref>

==Environmental impact==
Underwater archeology can have many impacts on the environment such as destroying habitats and disrupting wildlife that may be in the area of the archeological site. 

== History ==
{{empty section|date=July 2020}}

== Publications ==
Publication is an essential part of the archaeological process and is particularly crucial for underwater archaeology, where sites are generally not accessible and it is often the case that sites are not preserved in-situ.

The specialist journals on [[maritime archaeology]], which include the long established ''[[Nautical Archaeology Society#International Journal of Nautical Archaeology|International Journal of Nautical Archaeology]]'', ''The Bulletin of the Australasian Institute for Maritime Archaeology'' (AIMA)  and the recently launched ''Journal of Maritime Archaeology'' publish articles about maritime archaeological research and underwater archaeology.<ref name="JMA">{{cite web|url=https://www.springer.com/11457|title=Journal of Maritime Archaeology|work=springer.com|date=2024 }}</ref> However, research on underwater sites can also be published in mainstream archaeological journals, or thematic archaeological journals. Some institutions also make their unpublished reports, often called  'Grey Literature', accessible thereby allowing access to far more detail and a wider range of archaeological data than is otherwise the case with books and journals. An example is the works of the Department of Maritime Archaeology at the  [[Western Australian Museum]].<ref name="WAM">{{cite web|url=http://www.museum.wa.gov.au/research/research-areas/#maritime-archaeology/maritime-archaeology-publications|title=Research Areas|publisher=Western Australian Museum|access-date=20 October 2010}}</ref>

The public interest market is covered by a number of diving, shipwreck and underwater archaeology books, beginning with the works of [[Jacques Cousteau]].

The techniques of underwater archaeology are also documented in published works, including a number of handbooks,<ref name="IHUA">{{cite book|url=https://link.springer.com/book/10.1007/978-1-4615-0535-8|title=International Handbook of Underwater Archaeology|isbn=9780306463457|publisher=Springer|year=2002|series=The Springer Series in Underwater Archaeology|doi=10.1007/978-1-4615-0535-8|editor1-last=Ruppé|editor1-first=Carol V|editor2-first=Janet F|editor2-last=Barstad}}</ref><ref name="AU1">Archaeology Underwater, The NAS Guide to Principles and Practice; eds Martin dean, Ben Ferrari, Ian Oxley, Mark Redknap and Kit Watson. Published by Nautical Archaeology Society, Archetype Press, 1992 {{ISBN|1-873132-25-5}}</ref> and [[Keith Muckelroy|Muckelroy]]'s classic work on Maritime Archaeology.<ref name="Muckelroy" />

== See also ==
*{{annotated link|Aerial archaeology}}
*{{annotated link|Archaeology of shipwrecks}}
*{{annotated link|Lighthouse Archaeological Maritime Program|abbreviation=LAMP}}
*{{annotated link|Maritime archaeology}}
*{{annotated link|Nautical Archaeology Society}}
*{{annotated link|Pantelleria Vecchia Bank Megalith}}
*{{annotated link|Remotely operated underwater vehicle}}
*{{annotated link|Sea Research Society}} (Shipwrecks & Underwater Archaeology)
*{{annotated link|Archaeology Discover Centre|aka=Underwater Archaeology Centre and Sunken Secrets}}
*{{annotated link|Underwater acoustics}}
*{{annotated link|Underwater search and recovery}}
*{{annotated link|Unidentified submerged object}} 
*{{annotated link|Wreck diving}}

== References ==
{{reflist|30em}}

== External links ==
{{Commons category}}
* [http://www.rpmnautical.org/ RPM Nautical Foundation]
* [http://www.maritimehistory.org/ Institute of Maritime History] {{Webarchive|url=https://web.archive.org/web/20190818085821/http://www.maritimehistory.org/ |date=2019-08-18 }}
* [http://nauticalarch.org/ Institute of Nautical Archaeology]
* [http://www.lampmaritime.org/ Lighthouse Archaeological Maritime Program (LAMP), St. Augustine, Florida]
* [https://web.archive.org/web/20071125175636/http://www.bris.ac.uk/archanth/postgrad/maritime.html Centre for Historical and Maritime Archaeology, University of Bristol]
* [http://www.cma.soton.ac.uk/ Centre for Maritime Archaeology University of Southampton]
* [https://web.archive.org/web/20060925194710/http://www.science.ulster.ac.uk/cma/ Centre for Maritime Archaeology, University of Ulster, Coleraine]
* [http://www.shipwrecks.com/ethics_in_underwater_archaeology.htm Capitalism versus Socialism in Underwater Archaeology] {{Webarchive|url=https://web.archive.org/web/20070501110350/http://www.shipwrecks.com/ethics_in_underwater_archaeology.htm |date=2007-05-01 }} by [[E. Lee Spence]]
* [https://web.archive.org/web/20100125015733/http://www.ecu.edu/maritime/ East Carolina University Maritime Studies]
* [http://www.nps.gov/submerged National Park Service Submerged Resources Center]
* [https://www.youtube.com/watch?v=aiWitrf6LEw Mystery Mardi Gras Shipwreck Short]
* [http://www.flpublicarchaeology.org/ Florida Public Archaeology Network]
* [https://web.archive.org/web/20170704233206/https://www.abc.se/~pa/uwa/ Nordic Underwater Archaeology]
* [http://gmsbc.blogspot.com/ Resources for maritime archaeologists]
* [http://vanth.perseus.tufts.edu/cgi-bin/ptext?doc=Perseus%3Atext%3A1999.04.0006%3Aid%3Dshipwrecks "Shipwrecks"  in Stillwell, Richard, William L. MacDonald, Marian Holland McAllister, eds. ''Princeton Encyclopedia of Classical Sites'', 1976, Includes alphabetized list of known wreck sites from Classical Antiquity.]{{dead link|date=December 2017 |bot=InternetArchiveBot |fix-attempted=yes }}
* [http://www.nps.gov/archeology National Park Service Archeology Program]
* [https://web.archive.org/web/20070508182338/http://www.science.ulster.ac.uk/cma/slan/ Submerged Landscapes Archaeological Network]
* [https://archive.today/20130212201422/http://www.sdu.dk/maritimearchaeology University of Southern Denmark Maritime Archaeology Program]
* [https://web.archive.org/web/20150924024137/http://www.guidrynews.com/story.aspx?id=1000012825 The "Mardi Gras" Shipwreck Project]
* [https://web.archive.org/web/20120624045802/http://www.arch.ox.ac.uk/ocma.html Oxford Center for Maritime Archaeology]
* [http://www.ieasm.org/ Institut Européen d'Archéologie Sous-Marine] {{Webarchive|url=https://web.archive.org/web/20170817003319/http://www.ieasm.org/ |date=2017-08-17 }}

{{Archaeology}}
{{Underwater diving|prodiv}}
{{Authority control}}

[[Category:Underwater archaeology| ]]
[[Category:Maritime archaeology]]
[[Category:Methods in archaeology]]