Swildon's Hole through route discovered on the Mendip Hills. Following a number of months of digging and blasting, the link was made in 1996 at the top of the Cowsh Avens Series, a climb above Sump 4. The water in the cave resurges in Wookey Hole Caves. This was first demonstrated (by pouring dye into the water) by Graham Balcombe and Jack Sheppard of the Cave Diving Group, who first passed Sumps 1 and 2 in the 1930s. Swildon's Hole Swildon's Hole is an extensive cave in Priddy, Somerset. At in length, it is the longest cave on the Mendip Hills. It
Wookey Hole Caves Farr a few days later for at a maximum depth of to emerge in the 25th chamber, a desolate, muddy place named "The Lake of Gloom". 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 () in 1977, then Rob Parker () in 1985, and finally by John Volanthen and Rick Stanton () in 2004. The pair returned again in 2005 to explore the sump to a depth