A video featuring a squid swarm attacking a research submarine has gone viral after being posted on Vine by Greenpeace.

As of Tuesday morning, the six-second video had been shared more than two million times since being posted in honour of October's annual Cephalopod Awareness Week, said John Hocevar, a marine biologist with Greenpeace. The informal celebration of octopuses, squid and their eight-armed kin takes place each year starting Oct. 8.

Hocevar said the squid are "used to being able to eat pretty much anything they find," so it makes sense for them to try their luck with the sub.

The squid in the video belong to a species known as opalescent squid, or "market squid," as the species often winds up in dishes such as calamari.

Sub disabled by squid

They weren't as big as they look in the video – they're only about half a metre long. But they could still be dangerous.

Because there were such thick swarms of them, on two occasions a squid got sucked through the submarine's thrusters and propellers, blowing fuses and disabling the sub's ability to move around, Hocevar said. That forced Greenpeace to abort two dives and resurface early.

The dives were part of the environmental group's 2007 and 2012 expeditions to survey the seafloor habitat of the deep sea canyons in the Bering Sea.

Hocevar said Greenpeace had been calling for protection for those habitats, but the North Pacific Fishery Management Council, which regulates fisheries in that region off the coast of Alaska, said there wasn't enough information about them to justify special protection.

Following the Greenpeace surveys, which found a rich habitat of deep sea corals and sponges swarming with fish and marine life, the council has begun two processes that could lead to protection for the canyons.

"It's going too slowly," Hocevar said. "The ambition isn't what we'd like to see. But we're working on that."