Lasers beamed from space have detected lakes of water under 2,300 feet of compressed snow and ice below Antarctic ice.
About 90 percent of the world's fresh water is locked in the thick ice cap that covers Antarctica.
If it all melts it could cause a 20-foot increase in world sea levels. Even a 39-inch sea level rise could cause havoc in coastal and low-lying areas around the globe, according to a World Bank study released this week.
One lake that measured roughly 19 miles by 6 miles caused a 30 foot change in elevation of the snow at the surface when it drained over a period of about 30 months.