The Oceanbreaker was originally forged in Asgard along with Mjolnir, and had the ability to manipulate the oceans or the sea life within them. Originally given to Nekkron, following the original defeat of the Serpent, Cul. Nekkron was imprisoned in his hammer along with the rest of the Worthy and hidden within the dark areas of Asgard. Following the Serpent's freedom centuries later, the Oceanbreaker landed in the Atlantic Ocean where the villain, Attumma found it and became Nekkron.
Using the hammer, Nekkron not only destroyed new Atlantis but also mutate Tiger Shark and other known enemies of Namor, the Sub-mariner and launched at attack on Canada before he was driven back by Alpha Flight and later the Defenders. Following the defeat of the Serpent, the Oceanbreaker returned to the depths of the Atlantic Ocean where Namor has been keeping it guard until recently Sin and Crossbones took the hammer.