By SUSAN MONTOYA BRYAN, Associated Press Writer Thu Jul 24, 7:16 AM ET

FORT STANTON CAVE, N.M. - Hundreds of feet beneath Earth's surface, a few seasoned cave explorers venture where no human has set foot. Their headlamps illuminate mud-covered walls, gypsum crystals and mineral deposits.
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The real attraction, though, is under their shoes.

A massive formation that resembles a white river spans the cave's floor. A closer examination reveals that the odd formation is an intricate crust of tiny calcite crystals.

Many miles inside the Arctic Circle, scientists have found elusive vents of scalding liquid rising out of the seafloor at temperatures that are more than twice the boiling point of water.

The cluster of five hydrothermal vents, also called black smokers, were discovered farther north than any others previously identified. The vents, one of which towers four stories high, are located on the Mid-Atlantic Ridge between Greenland and Norway, more than 120 miles farther north than other known vents.