Clear Lake, the "lake born of fire", is the headwaters of the McKenzie River and was formed 3000 years ago when lava from Sand Mountain reached the river and backed up water to form the lake.
The original forest that had lined the river banks was submerged. Remnants of some of these submerged trees still stand under 120 feet of water and are visible from the trail and by boat. The nearly freezing temperature of the lake makes it unsuitable for swimming.
A picnic shelter, built by the Civilian Conservation Corp, is situated at the day use area near the resort.
Osprey and bald eagles, and native cutthroat trout call the lake home. Non-native rainbow and brook trout are also found in the lake.