Imagine you’re a 16th century Scandinavian sailor. Alright, I’ll help you. Just pretend you’re drunk and sway around a bit like you’re on a bobbing ship. And you have an eyepatch for good measure.

Now comes along Olaus Magnus. He hands you the most magnificent map you’ve ever seen – his Carta Marina, which happens to also include profoundly bizarre and ferocious sea monsters. Some are big enough to be mistaken for islands, others have blades on their backs for slicing open ships, and almost all have a taste for human meat.

You’re no longer lost, but unfortunately for you, you’ve gone catatonic with fear, because you’re holding what is perhaps history’s premier document of sea monster lore. And you’re on the sea.

In a beautiful new exploration of the Carta Marina, Sea Monsters: A Voyage Around the World’s Most Beguiling Map, scholar Joseph Nigg dives deep into the history and wide influence of Olaus’ bizarre creatures. “It’s like today’s whale-watching tours,” Nigg told WIRED via email, “but this one is up a seam in time, just as medieval thought was fading and marine zoology was in its infancy.”

“I’ve always been fascinated by how the imagination creates its own beasts from those of the actual animal kingdom,” he added. “By their very size, the medieval monsters in the northern seas of the Carta Marina dominate the hundreds of historical, cultural, and natural history figures on the map. To Olaus, the hearsay monsters were just as real as familiar land animals.”

Take the ziphius, shown above, which gets its name from xiphias, Greek for sword. It is so named because it swashbuckles all over the high seas, “doing mischief” by cutting open vessels with its sword-like dorsal fin. The critter has the head of an owl, which Olaus just calls “ugly.” And he can’t even bring himself to name the monster that’s in the process of taking a bite out of the ziphius, though if I were to take a stab at it, it’d be the stink-eyed saber-tooth mohawk fish. In the ziphius’ mouth is a seal, whose own mouth is agape, as if to say, “Oh, dang.” And the inspiration here, writes Nigg, is likely the orca, which has a similar dorsal fin and propensity for eating seals and sea lions in the gutsiest way possible.

We’ve compiled the most fearsome, weirdest, and most ridiculous creatures from Nigg’s book, which is available September 15. So come with us now on a journey through rough waters and nasty, big, pointy teeth. 

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