Nemo Peak volcano at the northern end of Onekotan Island in the northern Kuriles is truncated by two nested calderas of preglacial age, the largest of which is 10 km in diameter and extends to the northern coast. A third 5-km-wide caldera formed about 25,000 years ago by collapse of an interglacial cone that was constructed over the glaciated surfaces of the earlier calderas. The 1018-m-high central cone of Nemo Peak is composed of two coalescing andesitic cones that were constructed at the SW side of the youngest caldera and formed in four stages beginning in the early Holocene about 9500 years ago. Construction of the central cone has left the crescent-shaped Chernoe Lake at the NE end of the youngest caldera; lava flows from Nemo Peak form the broad SW shoreline of the lake. The final activity built a lava dome that completely overtops a 350-m-wide crater and has a 150-m-wide crater at its summit. Historical eruptions of Nemo Peak date back to the early-18th century.