Editing Wookey Hole Caves (section)

===Exploration===
[[File:Wookey Hole caves - geograph.org.uk - 1250476.jpg|thumb|left|upright|An underground lake in the first chamber]]

The cave as far as the third chamber and side galleries has been known since at least the Iron Age period.{{sfn|Barrington|Stanton|1977|page=179}} Before the construction of a dam at the resurgence to feed water to the paper mill downstream, two more chambers (the Fourth and Fifth) were accessible. Further upstream the way lies underwater. Diving was first tried by the [[Cave Diving Group]] under the leadership of [[Graham Balcombe]] in 1935. With equipment on loan from [[Siebe Gorman]], he and [[Penelope Powell|Penelope ("Mossy") Powell]] penetrated {{convert|170|ft|m|sigfig=2|abbr=on|order=flip}} into the cave, reaching the seventh chamber, using [[standard diving dress]]. The events marked the first successful [[cave diving|cave dives]] in Britain.<ref>{{Cite web| title=UK Caves Database | url=http://www.ukcaves.co.uk/ | access-date=23 February 2007}}</ref><ref name="BuxtonCDG">{{Cite web|url=http://www.cavedivinggroup.org.uk/Essays/History/JBArticle.html|title=The Cave Diving Group|last=Buxton|first=John S.|publisher=CDG|access-date=28 September 2008|archive-date=31 October 2008|archive-url=https://web.archive.org/web/20081031073104/http://www.cavedivinggroup.org.uk/Essays/History/JBArticle.html|url-status=dead}}</ref>

Diving at Wookey resumed in early June 1946 when Balcombe used his homemade respirator and waterproof suit to explore the region between the resurgence and first chamber, as well as the underground course of the river between the third and first chambers. During these dives, the Romano-British remains were found and archaeological work dominated the early dives in the cave. The large ninth chamber was first entered on 24 April 1948 by Balcombe and Don Coase. Using this as an advance dive base, the 10th and then 11th chambers were discovered. The way on, however, was too deep for divers breathing pure oxygen from a closed-circuit [[Diving rebreather|rebreather]]. The [[List of UK caving fatalities|cave claimed its first life]] on 9 April 1949 when Gordon Marriott lost his life returning from the ninth chamber.<ref name="farr">{{cite web|last=Farr |first=Martyn |title=60 years in a cave |url=http://www.divernetxtra.com/technol/cave896.htm |publisher=Divernet |access-date=17 November 2013 |url-status=usurped |archive-url=https://web.archive.org/web/20140417030059/http://www.divernetxtra.com/technol/cave896.htm |archive-date=17 April 2014}}</ref><ref>{{cite web|title=A Century of British Caving|url=http://www.sat.dundee.ac.uk/~arb/cpc/century.html|publisher=Craven Pothole Club|access-date=17 November 2013}}</ref> Another fatality occurred in 1981 when Keith Potter was drowned on a routine dive further upstream.<ref>{{cite web|last=Rose|first=Dave|title=Keith Potter|url=http://www.oucc.org.uk/procs/proc10/potter.htm|work=Proceedings 10 : "Pozu del Xitu"|publisher=Oxford University Cave Club|access-date=17 November 2013}}</ref><ref>{{cite journal|title=Cave Rescues and Incidents for the Year ending 31 December. 1981|journal=Belfry Bulletin|date=June–July 1982|volume=410/411|url=http://www.bec-cave.org.uk/index.php/publications-mainmenu-32/belfry-bulletin-mainmenu-33/451-belfry-bulletin-no-410411-junejuly-1982?showall=&start=2}}</ref>

Further progress required apparatus that could overcome the depth limitation of breathing pure oxygen. In 1955, using an [[Aqua-lung|aqualung]] and swimming with fins, Bob Davies reached the bottom of the 11th chamber at {{convert|15|m|ft|abbr=on}} depth in clear water and discovered the 12th and 13th chambers. He got separated from his guideline and the other two divers in the 11th chamber, ending up spending three hours trapped in the 13th chamber, and had much trouble getting back to safety.<ref>{{Cite web| url=http://www.cavedivinggroup.org.uk/Essays/History/1950.html| title=CDG History 1950–1959| publisher=Cave Diving Group| access-date=12 July 2012}}</ref> Opinion hardened against the use of the short-duration aqualung in favour of longer-duration closed-circuit equipment. Likewise, the traditional approach of walking along the bottom was preferred over swimming. Employing semi-closed circuit nitrogen-oxygen rebreathers, between 1957 and 1960 John Buxton and Oliver Wells went on to reach the elbow of the [[sump (cave)|sump]] upstream from the ninth chamber at a depth of {{convert|22|m|ft|abbr=on}}.{{sfn|Farr|1991|page=75}} This was at a point known as "The Slot", the way on being too deep for the gas mixture they were breathing.
[[File:Cave diving equipment.JPG|thumb|Cave diving equipment in the museum at Wookey Hole Caves]]
A six-year hiatus ensued while [[Open circuit scuba|open circuit]] air diving became established, along with free-swimming and the use of neoprene [[wetsuit]]s. The new generation of cave diver was now more mobile above and under water and able to dive deeper. Using this approach, Dave Savage was able to reach air surface in the 18th chamber (chambers did not have to have air spaces to be so named; they were the limits of each exploration) in May 1966. A brief lull in exploration occurred while the mess of guidelines laid from the ninth chamber was sorted out before John Parker progressed first to the large, dry, inlet passage of the 20th chamber, and thence followed the River Axe upstream on a dive covering {{convert|152|m|ft}} at a maximum depth of {{convert|24|m|ft}} to the 22nd chamber where the way on appeared to be lost.{{sfn|Farr|1991|page=98}}{{sfn|Hanwell|Price|Witcombe|2010}}

Meanwhile, climbing operations in the ninth chamber found an abandoned outlet passage that terminated very close to the surface, as well as a dry overland route downstream through the higher levels of the eighth, seventh and sixth chambers as far as the fifth chamber. These discoveries were used to enable the show cave to be extended into the ninth chamber and the cave divers to start directly from here, bypassing the dive from the third chamber onwards.<ref>{{cite web|title=Cathedral Cave|url=http://www.wookey.co.uk/cathedral-cave/|publisher=Wookey Hole Caves|access-date=24 November 2013|archive-date=2 December 2013|archive-url=https://web.archive.org/web/20131202223404/http://www.wookey.co.uk/cathedral-cave/|url-status=dead}}</ref> The way on from the 22nd chamber was at last found by Colin Edmond and [[Martyn Farr]] in February 1976 and was explored until the line ran out. A few days later Geoff Yeadon and Oliver Statham somewhat controversially reached the 23rd chamber after laying just a further {{convert|9|m|ft}} of line. After a further three short dives they surfaced in the 24th chamber to be confronted by what Statham described as "a magnificent sight—the whole of the River Axe pouring down a passage {{convert|40|ft|m|disp=sqbr}} high by {{convert|5|ft|spell=in|disp=sqbr}} wide" terminating in a blue lake after {{convert|90|m|ft}}. This lake was dived by Farr a few days later for {{convert|90|m|ft}} at a maximum depth of {{convert|18|m|ft}} to emerge in the 25th chamber, a desolate, muddy place named "The Lake of Gloom".{{sfn|Farr|1991|pages=103–106}}

The 25th chamber represents the furthest upstream air surface in Wookey Hole Cave. From here the River Axe rises up from a deep sump where progressive depth records for cave diving in the British Isles have been set: firstly by Farr ({{convert|45|m|ft|abbr=on|disp=or}}) in 1977, then Rob Parker ({{convert|68|m|ft|abbr=on|disp=or}}) in 1985, and finally by [[John Volanthen]] and [[Richard Stanton (cave diver)|Rick Stanton]] ({{convert|76|m|ft|abbr=on|disp=or}}) in 2004.<ref>{{Cite news|url=http://news.bbc.co.uk/1/hi/england/somerset/3703800.stm|title=Divers head for new depth record|publisher=BBC|access-date=10 November 2008 | date=30 September 2004}}</ref><ref>{{cite web|title=Rick Stanton |url=http://www.divernet.com/other_diving_topics/cave_diving/160916/rick_stanton.html |publisher=Diver Net |access-date=9 December 2013 |url-status=dead |archive-url=https://web.archive.org/web/20131214070320/http://www.divernet.com/other_diving_topics/cave_diving/160916/rick_stanton.html |archive-date=14 December 2013}}</ref> The pair returned again in 2005 to explore the sump to a depth of {{convert|90|m|ft|abbr=on}}, setting a new British Isles depth record for cave diving.{{sfn|Hanwell|Price|Witcombe|2010}} This record was broken in 2008 by Polish explorer [[Artur Kozłowski (speleologist)|Artur Kozłowski]], then later again by [[Michal Marek]], on dives in [[Pollatoomary]] in [[Republic of Ireland|Ireland]].<ref>{{cite news| last=Gallagher| first=Emer| newspaper=[[The Mayo News]]| title=Explorer plunges to new depths in Mayo| url=http://www.mayonews.ie/index.php?option=com_content&id=4721| date=16 July 2008| access-date=21 September 2011}}</ref><ref name=onet-may2019>{{cite web| title=Polak zginął podczas nurkowania w Irlandii| date=16 May 2019| website=wbi.onet.pl| url=https://wbi.onet.pl/irlandia-nie-zyje-36-letni-michal-marek-z-galway/n28m88b| language=pl| access-date=18 May 2019}}</ref>
Taking advantage of the tunnel driven through to Chamber 20 by the show cave management in 2015, a team began seriously to investigate the leads in that area. One small passage was pushed to a sump that was dived through to Sting Corner in Chamber 24. In 2020 a dry connection was made to the same location.<ref name="descent277" />

During 1996–1997 water samples were collected at various points throughout the caves and showed different chemical compositions. Results showed that the "Unknown Junction", from where water flows to the static sump in the 22nd chamber by a different route from the majority of the River Axe, is upstream of the sump in the 25th.{{sfn|Chapman|Gee|Knights|Stell|1999|pp=107–113}}