Uunabat

A powerful magic user named Uunabat uses illicit means to sneak into the water plane in search of elemental magic runes. When he arrived, he used the runes to release a Frost Blight on the Tritons, destroying critical infrastructure and killing millions of Triton.

This tragedy incurred the wrath of Rutar, God of the Water Plane, who retaliated by punishing the entire mortal plane with an ice age. He also closed all but one portal between the Water and Mortal plane, and sent his children to guard the remaining gateway. His children, two enormous Kraken, sit on either side of the whirlpool created by the gateway.