The "Treaty of Commerce, Navigation and Delimitation" was concluded in 1855, and the border was established between Iturup and Urup.
Najvišji točki v celotnem otočju sta 2.339 m visok vulkan na otoku Atlasov, na severnem koncu otočja in 1.819 m visok vulkan na otoku Kunashir, na južnem koncu otočja.