The Tao-Rusyr Caldera is a stratovolcano located on Onekotan Island, in Russia’s Far East. Roughly 7.5 kilometers (4.6 miles) wide, it contains the waters of Kol'tsevoe Lake and a large symmetrical cone, Krenitsyn Peak, which rises from the lake. Onekotan is part of the Kuril Islands, a volcanic archipelago and segment of the “Ring of Fire” — a path of tectonic activity that circles the Pacific Ocean.