Crystal Cave, Sequoia National Park, California This marble cave in the Giant Forest region is between the Ash Mountain entrance of the park and Giant Forest. The cave is a constant 9 °C °F), and only accessible by guided tour.
The second longest sea cave in the world is Santa Cruz Island's Painted Cave off the coast of Ventura, California. Formed along a fault line, the length of the cave measures in at 1227 feet, and the entrance is 130 feet high. by mikebaird