Mendip Hills to the development of cave diving in Britain. The first cave dive was attempted at Swildon's Hole in 1934, and the first successful dive was achieved the following year at Wookey Hole Caves, which has the deepest sump in Britain at 76 m (250 ft). The cave complexes at St. Dunstan's Well Catchment, Lamb Leer, and Priddy Caves have been identified as Sites of Special Scientific Interest. The deepest cave in the Mendip Hills is Charterhouse Cave with a vertical range of . Many caves in the Mendip area were excavated for archaeological and natural history studies by pioneer explorer
Cheddar Gorge When this melted during the summers, water was forced to flow on the surface, and carved out the gorge. During warmer periods the water flowed underground through the permeable limestone, creating the caves and leaving the gorge dry, so that today much of the gorge has no river until the underground Cheddar Yeo river emerges in the lower part from Gough's Cave. The river is used by Bristol Water, who maintain a series of dams and ponds which supply the nearby Cheddar Reservoir, via a diameter pipe that takes water just upstream of the Rotary Club Sensory Garden, a public