Blue Lake is a series of at least 3 overlapping explosion craters (maars), located along a NE trend slightly east of the crest of the Cascade Range. The best-known crater, Blue Lake Crater contains a blue lake (800m x 300m) and is probably the youngest. It formed by an eruption about 1300 years ago. It lies immediately west of the popular recreation area of Suttle Lake.
A chain of spatter cones 6 km to the SSW and about 4 km NE of Mount Washington aligned with Blue Lake crater. Its lavas are similar to those found at Blue Lake, suggesting that this row of vents may have been erupted at the same time and was fed by the same magma chamber.
