Wookey Hole Caves then passes through major cave systems such as Swildon's Hole, Eastwater Cavern and St Cuthbert's Swallet, around Priddy, but 95% is water that has percolated directly into the limestone. The southern slopes of the Mendip Hills largely follow the flanks of an anticline, a fold in the rock that is convex upwards and has its oldest beds at its core. On the Mendips the crest of the anticline is truncated by erosion, forming a plateau. The rock strata here dip 10–15 degrees to the southwest. The outer slopes are mainly of Carboniferous Limestone, with Devonian age Old Red Sandstone exposed
Wookey Hole Caves of , setting a new British Isles depth record for cave diving. This record was broken in 2008 by Polish explorer Artur Kozłowski on a dive in Pollatoomary in Ireland. During 1996–1997 water samples were collected at various points throughout the caves and showed different chemical compositions. Results showed that the location of the "Unknown Junction", from where water flows to the static sump in the 22nd chamber by a different route from the majority of the River Axe, is upstream of the sump in the 25th. There are old legends of a "witch of Wookey Hole", which are still