Sharknarok is a viking shark that was captured by a wizard inside an ice monolith during the middle ages.
Many years after that, he was finally able to escape from his ice prison.

He can summon magic boomerang axes that destroy everything in his way.

Sharknarok has been added to the standard shark progression right after Behemoth.

To get it you must unlock it in the Shark Store for 850,000 coins or 900 gems.