The Essex, an American whaleship from Nantucket, sank when it was attacked by a sperm whale in the Pacific Ocean in November 1820. Having lost their ship, the crew of the Essex attempted to sail to South America in whaleboats. After suffering from starvation and dehydration, most of the crew died before the survivors were rescued in February 1821.
In retelling the story of the crew's ordeal, Philbrick utilizes an account written by Thomas Nickerson, who was a teenage cabin boy on board the Essex and wrote about the experience in his old age; his account was lost until 1960 but was not authenticated until 1980 before being published, abridged, in 1984. The book also utilizes the better known account of Owen Chase, the ship's first mate, which was published soon after the ordeal.