Caves of the Mendip Hills then rising up a fracture in the rock. Few caves on the Mendip Hills are more than deep or a few kilometres in length, (with some notable exceptions, such as Swildon's Hole which is over long), but a number are complex with several levels of passages which have been abandoned by the water, for example those around Cheddar. The catchment area of the Cheddar Yeo, which rises in Gough's Cave, measures . Dye marking shows that some of the water travels underground for up to , taking up to 14 days to reach Cheddar. When Banwell Bone Cave was discovered
Wookey Hole Caves is of what is described in the guide book as "magnificent" river passage, high and wide, which finishes at a cascade falling from a long lake. There are also more than of high level passages above the river. The way on continues underwater for some reaching a depth of before surfacing in the 25th chamber – called the Lake of Gloom because of its thick mud deposits. The sump at the end of this has been dived for to a maximum depth of before gravel chokes prevented further progress. The end is located about northeast of the entrance. Wookey Hole