Jökulsárlón is a glacial lagoon, bordering Vatnajökull National Park in south Iceland. The lake has increased fourfold since the 1970s at varying rates because of melting of the glaciers. In 2009 it was reported to be the deepest lake in Iceland, at over 248m, as glacial retreat extended its boundaries. Huge blocks of ice are continually breaking from the glacier and chunks of iceberg float in the lagoon heading to the sea. The black sand beach with these large ice-chunks is often referred to Diamond Beach.