Swan Island is an island in the Alexander Archipelago, east of Admiralty Island, near the head of Seymour Canal, Southeast Alaska, United States. To its south is Tiedeman Island. It was named in 1890 by Lieutenant Commander Mansfield, USN. The first European to discover and chart the island was Joseph Whidbey, master of the HMS Discovery during George Vancouver's 1791-95 expedition, in 1794.