formerly SAGHALIEN (Jap. Karafuto), island, Far Eastern Russian Federation, in the Sea of Okhotsk, separated from the E coast of Russia by the Tatar Strait and from the Japanese island of Hokkaido to the S by La Pérouse Strait. Together with the Kuril Islands and several other islands, Sakhalin makes up Sakhalin Oblast, which has an area of 87,100 sq km (33,600 sq mi); pop. (2002 census) 546,695. The island of Sakhalin is some 965 km (600 mi) long from N to S; the width varies from about 24 to 160 km (15 to 100 mi). The principal city on the island and capital of the oblast is Yuzhno-Sakhalinsk. Mountain ranges traverse the island from N to S, and the chief rivers are the Poranay and the Tym. Industries include fishing, mining, and lumbering. Oil and coal are the main mineral products.

In 1855 the Russians and Japanese established a joint condominium over Sakhalin. According to the terms of the Treaty of Saint Petersburg (1875), however, Japan relinquished its claim to Russia in exchange for the Kuril Islands. Sakhalin was subsequently used as a penal colony. At the close of the Russo-Japanese War, the island was divided (1905) between the Japanese and the Russians. The portion of the island S of lat 50° N was assigned to Japan and the remainder to Russia. Following World War II, the entire island became (1945) a possession of the USSR. In May 1995 an earthquake devastated Neftegorsk, a town in northern Sakhalin, killing nearly 2000 people.