Editing Hydrographic survey (section)

=== Crowdsourcing ===
{{see also|Underwater exploration#Organisations, programs and projects}}
[[Crowdsourcing]] also is entering hydrographic surveying, with projects such as [[OpenSeaMap]],<ref>{{cite web|url=http://openseamap.org/fileadmin/user_upload/inhalt/PDF/Artikel_Hydro_International-2013-02.pdf|title=OpenSeaMap – the Free Nautical Chart |first1=Markus |last1=Bärlocher |date=March 2013 |website=openseamap.org |publisher=Hydro International |pages=28–33}}</ref> [http://www.teamsurv.eu TeamSurv] {{Webarchive|url=https://web.archive.org/web/20201229081738/http://www.teamsurv.eu/ |date=29 December 2020 }} and ARGUS. Here, volunteer vessels record position, depth, and time data using their standard navigation instruments, and then the data is post-processed to account for speed of sound, tidal, and other corrections. With this approach there is no need for a specific survey vessel, or for professionally qualified surveyors to be on board, as the expertise is in the data processing that occurs once the data is uploaded to the server after the voyage. Apart from obvious cost savings, this also gives a continuous survey of an area, but the drawbacks are time in recruiting observers and getting a high enough density and quality of data. Although sometimes accurate to 0.1 – 0.2m, this approach cannot substitute for a rigorous systematic survey, where this is required.  Nevertheless, the results are often adequate for many requirements where high resolution, high accuracy surveys are not required, are unaffordable or simply have not been done yet.

==== General Bathymetric Chart of the Oceans ====
{{excerpt|General Bathymetric Chart of the Oceans}}