Lava flow. Steam rising as a flow of molten rock (lava) enters the sea on the coast of Hawaii, the largest of the Hawaiian islands. The lava seen here is 1000-1200 degrees celsius in temperature. It has flowed more than 10 kilometres from the 1200-metre high Pu'u O'o crater in the east rift zone of the Kilauea volcano. Kilauea is one of the world's youngest and most active volcanoes. Lava reaches volcanoes from the Earth's interior through faults in the crust, and is forced through them by the high pressure within the Earth. The black rock of this coastline is made from old lava flows. Lava flows like this mean that the Hawaiian islands are still increasing in size.