Pu`u `O`o cone and surroundings as of March 2000 showing the area
covered (dark gray) by lava since February 1997 during episode 55. Inside
the crater of Pu`u `O`o, the "trough" is the drained lava pond of
September-October 1999. The central portion of the trough was briefly
filled with active lava in February 2000.
Puka Nui is the prominent collapse pit on the southwest flank of Pu`u `O`o, which is floored with lava erupted September-October 1999.