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
Nature reserves in the North Norfolk Coast Site of Special Scientific Interest Nature reserves in the North Norfolk Coast Site of Special Scientific Interest The North Norfolk Coast Site of Special Scientific Interest (SSSI) is an internationally important protected area in Norfolk, England. The SSSI is a long, narrow strip of coastal land that starts between Old Hunstanton and Holme-next-the-Sea, and runs east for about 43 km (27 mi) to Kelling. The southern boundary runs roughly west to east except where it detours around towns and villages, and never crosses the A149 coast road. It has an area of 7,700 ha (19,027 acres), and is additionally protected through Natura 2000, Special Protection