PU'U O'O VENT
This photograph was taken at the edge of the Pu'u O'o volcanic vent on Kilauea. A wall of volcanic rock surrounds a "lava pond." Molten lava fills the pond from below and overflows into lava tubes running down the mountain. When volcanic activity increases, lava wells up in the pond and may fountain over the top in a spectacular display. When volcanic activity decreases, the level of the pond drops and may form a hardened shelf, as seen in the left side of this photo.
    Lava tubes are formed when the surface of a lava flow cools and hardens. The solidified lava forms an insulating pipe in which molten lava can continue to flow underground to the sea.
    Yes, it's quite hot and smelly up there at the edge.