A series of volcanoes (up to 1539 meters) form the structure of this highly elongated island, 59 km long and 12 km wide, with an area of 227.6 sq. km. A partly submerged, 7.5 km wide caldera is situated at the northeastern tip of the island. In the center of the island lies Prevo Peak and down to the southwest lies Zavaritski Caldera, with three calderas contained within each other.
At the northeastern tip of the island is the Brouton Bay used by the Soviet Navy as a secret submarine base between 1987 and 1994. The remains of the base can be seen clearly on satellite images. Today the island is not inhabited, and several Soviet villages, like Kraternyy are deserted.
Believed currently to be under exploration to exploit the oil field from Simushir with air traffic and supply for Exxon under license from The Russian Federation. Details unknown!