The measurements revealed a previously unreported inflow of warm water under the ice from the north Atlantic.

BBC: Whales probe Arctic fjord's secrets

"We really want to know how much water is under the ice sheet, " she said.

CNN: NASA flights will study Antarctic ice changes

The technology will allow scientists to detect that water and see how much is present under the ice.

CNN: NASA flights will study Antarctic ice changes

The exercises train U.S. submarine crews to deal with craggy ice keels that extend 20 to 50 feet into the water, and varying salinity levels that complicate communications and navigation under the ice cap.

FORBES: U.S. Navy Scrambles for Piece of Arctic Pie

"The water is obviously icy cold and people can die of hypothermia very quickly or drown if they are caught under the ice, " he said.

BBC: Heavy snowfall forecast overnight

In 60 years the ice caps could melt and one fifth of the world's land will go under water.

BBC: Last Updated: Thursday May 08 2008 11:40 GMT