Dolphin and Union Strait lies in both the Northwest Territories (Inuvik Region) and Nunavut (Kitikmeot Region), Canada, between the mainland and Victoria Island. It is part of the Northwest Passage. It links Amundsen Gulf, lying to the northwest, with Coronation Gulf, lying to the southeast. The southeastern end of the strait is marked by Austin Bay. It gets its name from the two boats used by the Scottish naval surgeon and explorer John Richardson, who was the first known European to explore it in 1826.