Caves of Nanumanga is an underwater cave off the northern shore of Nanumanga, Tuvalu in western Polynesia. It was discovered by two scuba divers in 1986. The caves are located between 37 and 46 m (121 and 151 ft) below sea level,[1] down the wall of a coral cliff. Dark patches on the roof and walls and blackened coral fragments on its floor suggest the use of fire by ancient occupants.[2]