Photo of the Day 321

Cave Diver, Lechuguilla Cave, New Mexico, 1991

Photograph by Michael Nichols

Ultra-clear water makes this formation in New Mexico's Lechuguilla Cave look more precipice than pool. Called Lake Chandalar, spelunkers are advised to fill their canteens here without touching the water to avoid introducing bacteria that could cloud the crystalline pond.

(Photo shot on assignment for, but not published in, "Charting the Splendors of Lechuguilla Cave," March 1991, National Geographic magazine)