Blue Lake is thought to be of an average depth of 72 metres, but in places reaches 77 metres deep. The crater rim measures 1,200 metres (3,937 feet) by 824 metres (2,703 feet). The lake itself measures 1,087 metres (3,566 feet) by 657 metres (2,155 feet). The bottom of the lake is 30 metres (100 feet) below the level of the main street of the nearby town. The Blue Lake supplies the town with drinking water.