According to legend, this crafty turtle/whale/fish (the story varies between cultures on this point) is so big that sailors think it is an island. Excited to see land after so much time out on the water, sailors make landfall on the Aspidochelone. The beast then submerges, taking the unsuspecting sailors with it to the depths.
This particular tale has surfaced (pun intended) many times throughout human history, and is associated with figures as varied as Sinbad the (fictional) Sailor, Pliny the Elder, and Alexander the Great. Some say that this creature is the origin of the story of Jonah and the Whale, and others claim it is what Milton refers to as the Leviathan in “Paradise Lost”. The Aspidochelone is commonly believed to be associated with Satan – this creature tricks unsuspecting people into believing they’ve found what they most desire, and then takes them into the depths. Like Satan, Aspidochelone has many other names, including the asp turtle, Fastitocalon, and Balain.
Since the Aspidochelone is not as famous as other sea monsters, not as much effort has gone into debunking it. If the story is based on anything other than delirium from months at sea (recall that some of these folks believed that the top half of manatees resembled beautiful women), it is probably the observation of great whales at sea. While they look nothing at all like islands and it would be pretty difficult to land on one, they are impressively large animals.
Despite a shockingly low profile for a monster this size, aspidochelone has earned a spot as one of our favorite sea monsters.