Hanauma Bay is one of the most popular tourist destinations in Hawaii. Hanauma is both a Nature Preserve and a Marine Life Conservation District. Volcanic chains such as the Hawaiian Islands form as a result of the movement of a tectonic plate across fixed hot spot beneath the surface. The Hanauma Crater was created about 32,000 years ago during the latest burst of volcanic activity to occur on Oahu. The volcanic vents that formed Hanauma Crater opened on the sea floor. Upwelling magma vaporized the ocean water and steam explosions atomized the magma into fine ash. The explosions built cones of ash, which solidified into tuff. The eruptions shattered the sea floor—coral reef and basalt—and scattered pieces that are now embedded in the tuff. Wave erosion eventually cut through the low, southeast wall of the crater, forming the current bay.