Iceland

Lake Thingvallavatn is shown amid a landscape of snowy mountains.

Lake Thingvallavatn in Iceland used to freeze solid in the winter. Now, it is beginning to thaw. (Axel Kristinsson/Creative Commons 2.0)

Dartmouth College
On March 9, 2017, a strange crack appeared on the ice-laden surface of Thingvallavatn, the largest lake in Iceland.