Chatham Sound is a sound on the North Coast of British Columbia, Canada, located between Dundas and Stephens Islands and the Tsimpsean Peninsula near Prince Rupert, It was named in 1794 by Captain George Vancouver for John Pitt, 2nd Earl of Chatham, whose brother William Pitt, was later to become Prime Minister of Great Britain. Chatham Strait, in the northern Alaska Panhandle, was named for their father William Pitt, 1st Earl of Chatham.