With a highly elongated and convoluted shape, measuring around 200 km in length with a width averaging between 20 and 30 km, the island has an area of 3,200 km�. Much of this is mountainous and rugged terrain bordered by generally steep coasts. Like all the Kuril Islands, Iturup is a volcanic island. It is composed of a series of volcanoes that run the entire length of the island. These include the 1,220 m high Berutarube in the south, Atsonupuri (1,206 m) in the southwest, the twin volcanoes that gave rise to the Chirip Peninsula, the Grozny volcano group in the centre of the island (1,211 m), Stokap at 1,634 m, the Medvezhia group in the northeast (1,125 m), and the 1,205 m high Demon volcano at the northeast tip of the island. The island's elongate shape has arisen by the joining together of 12 separate volcanoes and mountain massifs, separated in the past and joined today by necks and mountainous cols.
Iturup is one of several islands lying at the southern end of the Kuril Chain that are claimed by Japan.
