The lake actually fills the caldera of a dormant volcano. Volcanic gas leaks into the lake, where it is absorbed into the cold waters at the bottom of the lake. On occasion—for example as the result of an earthquake—this gas is released, forming a deadly cloud which kills all living things within miles of the lake. Numerous settlements have been built near the lake, only to be wiped out by the sudden catastrophe. There are no current settlements, but the largest of the ruins is Bloodsalt.
For additional resources, see the Meta page.