Hang Mo So (Mo So Cave - in Khmer, "mo so" means "white stone"). The cave is located 27Km from Ha Tien, in Bình An commune, Kiên Lương district, Kiên Giang Province. The cave was used during the resistance war against France (1945 - 1954) and the war against the USA (1954 - 1975), as a military station and hospital. There is a small stream in the cave and some sections with deep water. As you enter the cave, you can hear the buzzing of the bats on the ceiling of the cave.