St Cuthbert's Swallet is the second longest, and most complex, cave on the Mendip Hills, in Somerset, England.

It forms a major part of the Priddy Caves system and water entering this swallet re-emerges at Wookey Hole.

[2] St Cuthbert's Swallet is part of, and lies underneath, the Priddy Pools Site of Special Scientific Interest.

[2] St Cuthbert's Swallet is a classic example of a deep phreatic cave system developed at a depth of not less than 85 metres (280 ft) beneath the water table.

St. Cuthbert's Swallet is attractive to cavers, for its complexity and size, reaching over 6.7 kilometres (4.2 mi) and a depth of 145 metres (476 ft), and having numerous large decorated chambers, forming phreatic mazes on seven distinct levels.