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 2^nd and 4^th 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).

Stemming from 13th century Norse lore, the Kraken is a sea monster said to dwell in the icy Atlantic between Norway and Greenland. Called “Hafgufa” (“Sea Mist”) in the old languages, it was first noted as one of two colossal creatures doing battle in the ocean, described as having crab-like features and being so large that it could swallow whales and ships whole. The Kraken could remain feeding on the seabed for months, eventually emerging at the surface with a head like an island, teeth like rocks in the water, and jaws so wide that boats could easily sail between them to collect fish. It was said that the whirlpool left in its wake when it dived again was as dangerous to sailors as an attack itself, though its behavior was compared to that of whales. By the 18th century, the Kraken’s description had changed to incorporate spiked tentacles, leading to speculation that fishermen had misidentified giant squid as spawn of the beast.