There really are sea monsters far beneath in the abyss, but they’re most unlikely ever to do us any harm. Long before Google Earth, cartographers often wrote three words on the edges of their maps, a shorthand for the mysteries beyond the known world: Here be monsters. The oceans became a repository for legions of terrifying creatures.

As sea monsters go, the kraken is king. It’s the size of a floating island and legend has it that it could cripple warships with its immense tentacles, dragging sailors into the dark unknown. As Alfred Tennyson put it: “Below the thunders of the upper deep/ Far, far beneath in the abysmal sea / His ancient, dreamless, uninvaded sleep/ The Kraken sleepeth.” Fishermen found a real kraken last month off the coast of Antarctica. The largest colossal squid ever seen, the 450 kg monster was taken to Te Papa Museum in New Zealand. It should provide remarkable insights into life in the cold southern oceans.

Only a few big squid are found every year, usually half-digested in the stomachs of sperm whales, or dead or dying near the surface of the ocean. No one has much idea where they live, what they eat, how they move or how they reproduce. Almost everything written about their behaviour is educated guesswork.

When a squid attacks the Nautilus in Jules Verne’s 20,000 Leagues Under the Sea, Captain Nemo is left holding back tears at the loss of a crewmate. In reality, giant squid are less diabolical: a large specimen might eat 50 kg of food a day but probably does it by hovering quietly in the water, waiting for some smaller squid or large fish to hove into view. The kraken described by Tennyson had more in common with the colossal squid, thought to be a more aggressive predator, which roams at depths of 2,000m. But, so far, even they haven’t pulled any ships into whirlpools, sailors and all.

Whatever fear there is of these unremitting terrors deep in the ocean, we can take comfort from something hinted at by Tennyson, and proved right time and again. The monsters of

the deep probably aren’t meant to meet people. Most, like his kraken, come to a withering end if they stray out of their comfort zones in the deep ocean. “In roaring he shall rise and

on the surface die.”