The caldera which contains Heaven Lake was created by a major eruption in 969 AD (± 20 years)
The lake has a surface elevation of 2,189.1 m (7,182 ft). The lake covers an area of 9.82 km² (3.79 sq mi) with a south-north length of 4.85 km (3.01 mi) and east-west length of 3.35 kilometres (2.08 mi). The average depth of the lake is 213 m (699 ft) and maximum depth of 384 m (1,260 ft). From mid-October to mid-June, it is typically covered with ice.