 Off the south end of Little Sark are the Venus Pool and the Adonis Pool, both natural swimming pools whose waters are refreshed at high tide.The whole island is extensively penetrated at sea level by natural cave formations that provide unique habitats for many marine creatures, notably sea anemones, some of which are only safely accessible at low tide.Sark is made up mainly of amphibolite and granite gneiss rocks, intruded by igneous magma sheets called quartz diorite.