The Crystal Caves are a pair of caves in Hamilton parish, in Bermuda, whose ceilings crowded with soda-straw stalactites hang over a lake of clear tidal seawater seventeen metres deep, crossed on a pontoon bridge that floats on the water and rises and falls with the Atlantic outside, and they were found in 1907 by two boys chasing a lost cricket ball into a hole. Almost all of the island's 150-odd known caves are crammed into one patch of ground, the Walsingham formation, about two square kilometres of the island's oldest limestone riddled with holes, and Crystal Cave is the finest, ninety-odd steps dropping into cool still air and ending on a bridge held up by nothing but water over Cahow Lake, whose bottom shows through the clarity; the ceiling is hung with soda straws, thin hollow tubes of limestone built one drip at a time over tens of thousands of years, with thicker stalactites and columns among them, all lit from below so that the ceiling doubles in the lake. The water is the sea, since the cave connects underground to the ocean, and it rises and falls a metre with the tide, so the bridge floats to keep pace.
The clear water beneath the pontoon is not empty, since tiny crustaceans found nowhere else live in the darkness of the flooded passages, and divers have mapped the connections between the caves. Fantasy Cave on the same ticket was shut for some sixty years and reopened in 2001 with newer paths and lighting, deeper and with an amber chamber of thicker formations, and the two are done in an hour. The caves lie near the eastern end of the island, beside the road to St George's, and Mark Twain visited them in 1908 and wrote of the crystal palace. The Crystal Caves are a ceiling of straws over a piece of the sea, and the bridge across floats on the tide.