Lamb Leer (grid reference ST544550) is a 14.59 hectare (36.04 acre) geological Site of Special Scientific Interest between East Harptree and Priddy in the Mendip Hills, Somerset, notified in 1983.

The cavern is a fragment of a very ancient major cave system which now contains one of the largest chambers in the Mendip Hills.

[5] In 1974, an un-lifelined caver fell off a ladder in Lamb Leer Cavern, and a novice caver who was at the bottom of the ladder was badly injured, resulting in legal action against the caving club for damages.

[7] The system is dry, lying well above the present day water-table, and it is thought that the passages may well have originated before the Ice Age (Pleistocene Period) began.

Sediments preserved in the caves are important as they allow geologists to study the record of the changing environmental conditions which occurred over this long period of time.