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
North Norfolk Coast Site of Special Scientific Interest is also a car park further east on Beach Road, Wells-next-the-Sea. Cley Marshes visitor centre and car park are to the south of the A149, opposite the main reserve. The centre and four of the five bird hides are accessible to people with limited mobility. Their proximity to the main coast road means that the reserves can be accessed by bus as well as car. The Peddars Way National Trail runs the length of the SSSI, and only short sections of this part of the long distance footpath venture south of the SSSI boundary. A 2005 survey at six North