A sperm whale rammed and sank the Nantucket whaleship Essex on 20 November 1820. The crew arrived at Henderson on 20 December in three small whaleboats. They found the island's only known drinkable water-source – a brackish spring on the north shore, exposed at half tide – and ate fish, birds, eggs, crabs and peppergrass, but they had largely exhausted the available food within a week. On 27 December the three boats set sail for South America, leaving behind Thomas Chappel, Seth Weeks, and William Wright, who chose to stay. They survived until their rescue on 9 April 1821. In his account of the ordeal, Chappel reported having seen human skeletons in a cave. The report of sperm whale ramming the ship may have inspired Herman Melville to write "Moby-Dick"