This is an Icelandic delicacy called Hakarl. It is the putrefied flesh of a Greenland shark or the endangered Basking shark. The Greenland shark is poisonous so the locals have a peculiar way of preparing it, and I'll give you the jist of it.
Fishermen dig a hole in the sand and place the gutted shark in it for 2 or 3 months, allowing it to ferment in its own bodily fluids, many of which eventually run out into the sand. The the shark is hung to dry out for up to a year and it develops a nasty brown crust, which is mercifully cut off prior to eating.
The rotten shark is one of the strongest-smelling foods on the planet. Because it has been soaking in its own uric acid (yes that's pee) it comes out smelling like highly concentrated ammonia. It is so pungent that Gordon Ramsey puked after attempting to consume it. Eating the fermented fish is associated with strength and bravery, and for good reason. I cannot THINK of anyone who would voluntarily consume the rotten flesh of a poisonous animal.
I'm curious as to how someone would come up with the idea of burying an enormous fish for months to make it (barely) edible. Although it doesn't particularly appeal to me, it continues to amaze me how inventive isolated people can be in order to survive. Most Ikes I know are hardcore dudes, and this fish dish is proof that they are are crazier and tougher than most of you.