Sir Robert John Le Mesurier McClure, 1807–73, British arctic explorer. He entered the navy and in 1848 accompanied Sir James Clark Ross to the arctic. As a naval captain he was given command (1850) of the Investigator, one of the two ships that were to search the western part of the Arctic Archipelago for Sir John Franklin. Passing through the Bering Strait, he coasted along Alaska and Canada, then went by way of Prince of Wales Strait into the western part of Viscount Melville Sound. He wintered (1850–51) in Prince of Wales Strait and by a sledging journey along its shores reached Barrow Strait. He discovered McClure Strait and established the insularity of Banks Island. On the north coast of Banks Island the Investigator was frozen in the ice for several winters. Finally he abandoned ship in 1853 and by sledge retreated over Barrow Strait eastward across the ice to Dealy Island, where his party was ultimately rescued by Sir Edward Belcher's expedition. McClure became the first man to prove the existence of the Northwest Passage. Although he was censured for having returned without his ship, he was highly commended for his work and knighted in 1854.

McClure Strait, arm of the Beaufort Sea, c.170 mi (270 km) long and 60 mi (100 km) wide, Northwest Territories, Canada. It extends W from Viscount Melville Sound, between Melville and Eglinton islands on the north and Banks Island on the south. In 1954, U.S. icebreakers cut through the strait for the first time, opening the last obstacle to the shortest water route across the Canadian arctic region.