A massive squid has been caught on video attacking a Greenpeace submarine in the Bering Sea.

The squid can be seen in a Vine video lashing at the submarine with its tentacles, before it fires a burst of ink and swims away from the underwater vessel.

A second squid can be seen swimming nearby during the attack.

The video was posted to Vine on Friday, as part of Greenpeace's Cephalopods Week.

The submarine's passengers were exploring the Bering Sea between Russia and Alaska when they encountered the rare squid.