I almost posted about this a few weeks back but lost the link, here is an update on that story from CNN.com:
SANTIAGO, Chile (Reuters) — Scientists said that a lake in southern Chile that mysteriously disappeared last month developed a crack which allowed the water to drain away.
A buildup of water opened a crack in an ice wall along one side of the lake.
Water flowed through the crack into a nearby fjord and from there into the sea, leaving behind a dry lake-bed littered with icebergs, scientists told Chilean state television Tuesday.
“It looks like it’s slowly filling up with water again,” said Andres Rivera, a glacier expert who headed a team which recently flew over the lake in a bid to solve the mystery.
The lake is situated in the Magallanes region in Patagonia and is fed by melt-water from glaciers.
Earlier this year it had a surface area of 10-12 acres — about the size of 10 soccer fields.
Scientists noticed it had disappeared during a routine patrol of the area in May.