The Portuguese explorer Ferdinand Magellan may have sighted Caroline Island on 4 February 1521. The first recorded sighting of Caroline Island by Europeans was on 21 February 1606, by the Portuguese explorer Pedro Fernández de Quirós, who named the island San Bernardo, and who wrote an account of his voyage. The island was next seen by Europeans on 16 December 1795, when the British naval officer William Robert Broughton of named it Carolina, after the daughter of Philip Stephens, the First Secretary of the Admiralty. The island was sighted in 1821 by the English whaler "Supply", and was then named "Thornton Island" for the ship's captain. It was also recorded in the 19th century as Hirst Island and Clark Island.