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The Discovery & Exploration Of Wookey 23 - 25

by Chris Batstone

The numbering of sumps in Wookey can for some seem strangely complex.  From one to nine the system is relatively easy to understand, there being airspace between the sumps.  From 9 to 22 things become slightly obscure.  To clarify this however, the reader should be aware that between 9 and 22 the cave is totally submerged, except for the 20th chamber the numbering is merely to signify stages in exploration.  The conventional sump numbering system is used beyond the 22nd chamber.


By early 1976 the Cave Diving Group attempts to find the continuation of the cave system beyond the 22nd chamber had been fruitless.  Despite this a number of divers were still enthusiastic enough to keep up the search.

On February 21st1976, Colin Edmunds and Martyn Farr had gone in to 22 to investigate the far sump. Previously Parker had reported that "it was static and did not go."  During their investigation of the sump they found an opening much like the "slot" in 15.  They explored the passage beyond until the line ran out.  They had explored 300ft of passage down to a depth of 65ft.  The two divers were forced to return to base having no more line with which to explore further.

A day later on the 23rd February, two more divers Oliver Statham and Geoff Yeadon went in to push the sump further.  Statham led the dive, he followed Edmunds line to the limit of the previous dive. Then tying on his own line pushed on to surface 60ft further in Wookey 23.  He was soon joined by Yeadon who was following behind surveying as he went. They had found a passage 40 x 25ft with a sandy floor.

The next sump did not seem very inviting so they spent some time investigating an aven for alternative routes, none were found.  Statham dived sump 23.  This he found to be a series of short sumps.  Each time he surfaced he found deep water high rifts with dry passage leading off, but steep mud banks to make his exit difficult.  He found that exiting from the pool in "24" was difficult due to its steep mud bank.  He was soon joined by Yeadon who helped him out of the pool onto the mud bank.

Yeadon wandered off along the large sandy passage they had found, looking for the next "inevitable sump".  Excitedly he shouted to Statham to "de-kit".  The passage was not going to end in a sump just yet.  The two explored up the passage, where they heard the roaring sound of a large amount of water.  Climbing over some boulders they found the subterranean River Axe flowing in a passage 40ft high and 5f. wide.  They swam upstream against a very strong current, for approx. 150ft.  The passage opened out into a large Chamber, with a high level route leading off.  They stayed in the river passage which had narrowed to 2-3ft wide and about 50ft high.  After about 300ft they came to a cascade which they climbed, into a large chamber.  Here the high level passage mentioned earlier joined the river passage.  This chamber opened out to a lake.  The divers swam across the lake to investigate a rift, but no way on could be seen.  The water in the lake came up from under the left wall this then was the next sump (24).

On their return they made a quick survey and explored the high level passage; the total passage length was 2,000ft plus.

A week later on the 27th February Martyn Farr and Colin Edmunds were back.  Arriving at Sump 24 Farr dived reaching a depth of around 85ft. The way on was up a steeply inclined dip.  On his second attempt he reached an air surface.  His dive had been 350ft long finishing at a chamber (25) covered in thick deposits of mud.  He swam across it until he came to what he thought to be a bridge of rock.  Pulling himself up about 3ft out of the water he could see into another pool approx. 30ft in diameter.  He returned to Edmunds in 24 where they explored some side passages. They returned to 9:2 after 6¼ hours in the cave.

Farr and Edmunds returned to Wookey on the 10th April aiming to photograph the new extensions and have a look at the terminal sump (25).  On reaching 25 Farr christened the chamber the " Lake of Gloom".  He discovered that the rock bridge was in fact a solid rock wall.  Making impossible any attempt to dive through to the next pool.  However he managed to "de-kit" and climb over into the pool to make a quick inspection.  Finding that the sump was very large and deep and to dive further would require a good deal of support.

It was now apparent from the last pushing attempt that considerably more support would be needed to push any further.  With a dive of over 2000ft long and 80ft deep to 25.  The problems of high air consumption had to be considered, a large amount of extra air cylinders were needed.  The problems of decompression, too, had to be considered.  Decompression stops in cold water can be very wearing. To offset the cold, constant volume, drysuits were acquired.  These dry suits had the advantage of keeping in the body warmth, and counteracting the negative buoyancy at depth.  The major disadvantage of these suits is that they tend to cause overheating when the diver is not in the water.  A large amount of the equipment was obtained from sponsors who donated either equipment or money to the project.

Many weeks were spent practicing with the new equipment and techniques associated with it.  Numerous artificial aids were transported into the extensions; this included two lengths of rigid steel ladder to 25 to aid the scaling of the barrier wall.  To facilitate easy passage of the canals and climbs, these were roped up to assist the divers in high water conditions.

A water tracing exercise was also carried out on November the 27th.  Two tests were made.  One using rhodamine dye from 25.  This was detected at the resurgence after 9 hours.  The other test was made from St. Cuthbert’s Swallet.  140 grams was put into the sink and followed through the cave to sump 2.  But the dye was not subsequently detected at the resurgence after 56 hours.  It may be supposed that the amount of dye used was too small.

The Push

The 11th June 77 had been set for the assault on Sump 25.  In the preceding weeks the essential equipment had been transported to various parts of the cave ready for use.  The 9th Chamber was crowded with divers, supporters, television film crews, newspapermen and tourists.  The divers were Martyn Farr, Dave Morris, Colin Edmunds, Brian Woodward, Richard Stevenson, Paul Atkinson and George Bee.

Due to high water conditions the dive was postponed, although a performance was put on for the benefit of the media.  This also gave an opportunity to put the finishing touches to the final preparations.

The same team of divers were back at the cave on the 18th June.  Farr dived with Morris as back up diver.  The others went to 24 to help ferry and check the back up equipment. Leaving Morris in the Lake of Gloom, Farr dived down the Well, finding the line reel previously left in from the July '76 dive, at approx. 100ft depth.  He decided to follow the passage floor down.  Passage dimensions were approx. 4ft wide by 25ft high. Visibility was poor due to mud from the floor, which he disturbed as he swam.  At 135ft depth Farr came to a 10ft vertical drop.  He could see the passage continued on downwards.  Descending this he soon reached 150ft depth.  Here he dropped the line reel and made a rapid return to Morris at the Well to decompress.  The divers returned to 9:2 de-tackling as they went, making a short decompression stop before surfacing in 9:2 after a trip lasting 8 hours.

Although the main objective of the dive to push the final sump failed, the exercise has been useful, several lessons had been learnt.  Decompression and use of open circuit breathing mixtures have been established in cave diving, besides setting a new British cave diving depth record.

To the authors knowledge no further pushes have been made on sump 25 nor are any further planned, at the time of writing.  The story does not stop here, the events of the 1976-77 dives are just another chapter in the story.  As diving equipment and techniques improve, so divers will be able to push even farther and deeper into the sumps of Wookey Hole.

It is hoped this article has provided a clearer picture of events at Wookey Hole to date.

References: -

C.D.G. Newsleters No's '39 to 45 (new series)

B.C.R.A. Bulletin No 17 Aug 77.  Recent developments at Wookey Hole.