This massive steam plume was created when hot lava entered the sea along a Hawaii's Kalapana shoreline. The plume is thousands of feet high and rises above an open vent in a lava tube system at the sea's edge. At the base of the plume is a littoral cone, formed by volcanic fallout. When the ocean pounds the hot lava, it sets off steam explosions, which fill the surrounding air with hydrochloric acid.