Crystal Caves are located on the south shore road of the island, near Castle Harbour isthmus. These solution chambers are 40 m below the surface, and are formed from tidal pools with up to 30 m of water. The stalagmites reach up to 10 or 20 m in length. These caves formed not by downward percolating vadose water, throught the limestone, but rather from a horizontal movement of water through a completely saturated rock and collapse of the limestone, karsting. The steep entrance way is formed from some of this collapsed limestone.