The Sakhalin Region is the only federal subject in Russian located entirely on islands - predominantly the island of Sakhalin, which is immediately above Japan and has in the past even been part of the Land of the Rising Sun. Unsurprisingly a Japanese influence is noticeable in some areas. It is one of the most remote regions, being 10,400km from Moscow or 8½ hours on a direct flight. The administrative centre of the region is the city of Yuzhno-Sakhalinsk.
The main reason for visiting Sakhalin is for its nature as although it is larger than the island of Great Britain it only has a population of just under half a million people, meaning that most of the land is uninhabited and unspoiled. However often a local guide is required to explore remote parts of the island. You should also be careful as over 3000 wild bears live on Sakhalin. The Kuril Islands also form part of the Sakhalin Region, although they are also claimed by Japan and because of this issue no peace treaty has ever been signed after the Second World War between the USSR/Russia and Japan. The islands are unique and unlike any other part of Russia, however it is far from easy to visit them.