In several cultures from around the world, there is a common myth of a giant sea monster which has the appearance of an island when it surfaces from the ocean depths. Though its features vary from tale to tale, it is most often described as either a whale or an enormous turtle, with ridges on its back that are mistaken for mountains and forests when seen from afar. The first written account of such a creature dates back to Ancient Greece in the Physiologus, compiled sometime between the 2nd and 4th centuries AD, named as Aspidochelone. The term is a combination of the Ancient Greek words for asp (a type of snake) and turtle, referring to the cunning and deadly nature of the beast.
Stories of Aspidochelone tell of how it uses its vast island-like shell to lure unwitting sailors, offering a haven of sandy beaches and lush valleys. Once the doomed men have set foot on the monster’s back and lit their fires for warmth, Aspidochelone will begin to dive, dragging the sailors and their ships under the sea. For food, it emits a sweet scent to entice fish into its vicinity, easily devouring any living thing that gets ensnared by its trap. Examples of similar legends are those of Fastitocalon (an alternative name for Aspidochelone in an Old English poem), Zaratan (the Persian equivalent mentioned in the first voyage of Sinbad the Sailor), Jasconius (a giant fish in the Irish tale of Saint Brendan), and the Imap Umassoursa (an Inuit sea monster that appears as a flat island, tipping anyone nearby into the freezing waters).