The Torres Strait is the body of water which lies between Australia and Papua New Guinea. It is approximately 150km wide. To the south is Cape York, the northernmost extremity of the Australian state of Queensland. To the north is the Western Province of Papua New Guinea.

The strait links the Coral Sea to the east with the Arafura Sea in the west. It is very shallow, and the maze of reefs and islands make it difficult to navigate. In the strait lie the Torres Strait Islands, inhabited by the Torres Strait Islanders, a Melanesian people related to the Papuans. Several languages are spoken on the Torres Strait Islands, one of them being Torres Strait Creole.

The strait was first navigated by Luis Vaez de Torres, an either Spanish or Portuguese seaman who was second-in-command on the expedition of Pedro Fernandez de Quiros who sailed from Peru to the South Pacific in 1605. After Quiros's ship returned to Mexico, Torres resumed the intended voyage to Manila via the Moluccas. He sailed along the south coast of New Guinea, and probably saw the northernmost extremity of Australia.

In 1769 the Scottish geographer Alexander Dalrymple found Torres's report of this voyage in Manila, and it was he who named the strait after Torres.

In 1770 when James Cook annexed the whole of eastern Australia to the British Crown, the Torres Strait Islands were annexed along with them, and indeed Cook sailed through the strait after sailing up the Australian coast. They thus later became part of the British colony of Queensland, although some of them lie just off the coast of New Guinea. This became an issue when Papua New Guinea was moving towards independence from Australia in 1975. The Torres Strait Islanders insisted that they were Australians, but the Papua New Guinea government objected to complete Australian control over the waters of the strait.

Eventually an agreement was struck whereby the islands and their inhabitants remain Australian, but the maritime frontier between Australia and Papua New Guinea runs through the centre of the strait. In practice the two countries co-operate closely in the management of the strait's resources.

In 1982, Eddie Mabo and four other Torres Strait Islanders from Mer (Murray Island) started legal proceedings to establish their traditional land ownership. Because Mabo was the first-named plaintiff, it became known as the Mabo Case. In 1992, after ten years of hearings before the Queensland Supreme Court and the High Court of Australia, the latter court found that Mer people had owned their land prior to annexation by Queensland.

This ruling overturned the century-old legal doctrine of terra nullius ("no-one's land"), which held that native title over Crown land in Australia had been extinguished at the time of annexation. The ruling was thus of far-reaching significance for the land claims of both Torres Strait Islanders and Australian Aborigines.