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
Somerset Valley and to the south, on the clay substrate, are broad valleys which support dairy farming and drain into the Somerset Levels. There is an extensive network of caves, including Wookey Hole, underground rivers, and gorges, including the Cheddar Gorge and Ebbor Gorge. The county has many rivers, including the Axe, Brue, Cary, Parrett, Sheppey, Tone and Yeo. These both feed and drain the flat levels and moors of mid and west Somerset. In the north of the county the River Chew flows into the Bristol Avon. The Parrett is tidal almost to Langport, where there is evidence of two