Adopted 1 May 1934 on National Defence sheet 415a, Victoria, as labelled on British Admiralty Chart 2689, 1861 et seq, and on BC map 2A, 1913.

Source: BC place name cards, or correspondence to/from BC's Chief Geographer or BC Geographical Names Office

Named previously to Captain Richards's survey in 1858, probably by Captain Kellett or Lieutenant Commander Wood, 1846-47, in association with Discovery Island. Discovery Island was named after Captain Vancouver's ship, and Chatham was the name of the small consort ship of the Discovery, at the time under the command of Lieutenant Broughton. The vessel was doubtless named after the Earl of Chatham, who, when Vancouver sailed from England, was First Lord of the Admiralty. The Chatham was built at Dover, and is described as an "armed tender, mounting four three-pounders and six swivels, 135 tons burthen, and sheathed with copper". She was brig rigged, and carried a crew of fifty-five all told. After Broughton returned to England in 1793, Lieutenant Puget, of the Discovery, was placed by Vancouver in command of the Chatham.

Source: Walbran, John T; British Columbia Coast Names, 1592-1906: their origin and history; Ottawa, 1909 (republished for the Vancouver Public Library by J.J. Douglas Ltd, Vancouver, 1971)