The Caldera of the Okmok Volcano, Alaska, USA53.4N 168.1W
The circular caldera of Mount Okmok occupies much of Umnak Island, one of Alaska’s Aleutian Islands in the USA. The caldera is 5.8 mile (9.3 km) wide, cutting across the top of a large shield volcano.
The caldera rim can be observed in detail in this orthorectified image. Of particular interest are an eroded section through which the lake that once filled the caldera drained, visible around the 12 o’clock position, and Mount Okmok itself, the highest point of the volcano at over 3400 feet, visible around 10 o’clock.