The Fisher caldera, on western Unimak Island NE of Westdahl volcano, is 11 x 18 km elongated in a NE direction It formed around 9,400 years ago, accompanied by emission of large-volume pyroclastic flows that reached the Bering Sea and the Pacific Ocean. Two cones are located below the N rim, NE of its high point at Eickelberg Peak, which rises more than 900 m above three lakes on the caldera floor, one of which drains through a notch in the southern caldera rim. A large composite cone, Mount Finch, is found at the center of the caldera, which also contains a small breached cinder cone. Eruptions have occurred in the 18th and 19th centuries. Low-temperature fumaroles are located on the W flank of Mount Finch, and Turquoise Lake, at the base of the cone, emits hydrogen sulfide gas.