A mix of ropes and ladders eases access to Warren Cave, a labyrinth of passages melted from the ice by the volcano's heat. Small currents of air probably cause the scalloping around the cave's ... more 
A mix of ropes and ladders eases access to Warren Cave, a labyrinth of passages melted from the ice by the volcano's heat. Small currents of air probably cause the scalloping around the cave's entrance.© Carsten Peter/National Geographic Click here to see more National Geographic photos. less 
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Mon, Jun 18, 2012 7:00 PM EDT