The Lombok Strait is a strait connecting the Java Sea to the Indian Ocean, located between the islands of Bali and Lombok in Indonesia.
Its narrowest point is at its southern opening, with a width of only 18 km, but at the northern opening it is 40 km across. Total length is about 60 km.
The Lombok Strait is notable as one of the main passages for the Indonesian throughflow that exchanges water between the Indian Ocean and the Pacific Ocean.
It also marks the passage of the biogeographical division between the fauna of Indo-Malaysia and the distinctly different fauna of Australasia that is known as the Wallace Line, for Alfred Russel Wallace, who first remarked upon the distinction between these two major biomes here. When sea levels dropped during the Pleistocene ice age, Lombok was connected to Sumatra and the mainland of Asia and shared the Asian fauna, but the deep water of the Lombok Strait continued to keep Bali and the Lesser Sunda archipelago isolated.
