The Simpson Strait (68°32′N 097°30′W / 68.533°N 97.500°WCoordinates: 68°32′N 097°30′W / 68.533°N 97.500°W) is a natural, shallow waterway separating King William Island to the north from Adelaide Peninsula on Nunavut's mainland to the south. The strait, an arm of the Arctic Ocean, connects the Queen Maud Gulf with Rasmussen Basin's Rae Strait.
Simpson Strait measures 40 mi (64 km) long and 2–10 mi (3.2–16.1 km) wide, and there are several small islands within it: Albert, Beaver, Boulder, Castor, Chens, Club, Comb, Denille, Dolphin, Eta, Hook, Kilwinning, Pollux, Ristvedt, Saatuq, Sarvaq and Taupe.
George Back reached Simpson Strait in 1834, but did not name it.
In 1836, the Hudson's Bay Company wanted 'to endeavor to complete the discovery and survey of the northern shores of the American continent' and so it sent Thomas Simpson and Peter Warren Dease on an expedition. Simpson and Dease reached the Simpson Strait in 1839, and named it in honor of Simpson.