Visitors to Hawaii Volcanoes National Park stand atop an old cinder cone to watch an ash filled plume of sulfur dioxide gas and ash rising from the Halemaumau crater of Kilauea volcano in this Wednesday, March 26, 2008 file photo. Elevated sulfur dioxide levels from Kilauea volcano have forced the closure of Hawaii Volcanoes National Park on the Big Island Tuesday, April 8, 2008. [Agencies]