Caves of the Mendip Hills traverse from one cave to another through the underground rivers led to the development of cave diving; the first cave dive attempt in Britain took place at Swildon's Hole in 1934. The first successful cave dive in Britain was achieved the following year at Wookey Hole Caves, where the last sump is currently the deepest in Britain at . The cave complexes at St. Dunstan's Well Catchment, Thrupe Lane Swallet, Lamb Leer and Priddy Caves have been identified as geological Site of Special Scientific Interest. There are also caves within the Cheddar Complex SSSI. A selection of the better known
Cheddar, Somerset water pipe that is used to transport the water can be seen next to the sensory garden in Cheddar Gorge. It has been designated as a Site of Special Scientific Interest (SSSI) due to its wintering waterfowl populations. Cheddar Wood and the smaller Macall's Wood form a biological Site of Special Scientific Interest from what remains of the wood of the Bishops of Bath and Wells in the 13th century and of King Edmund the Magnificent's wood in the 10th. During the 19th century, its lower fringes were grubbed out to make strawberry fields. Most of these have been allowed