A maelstrom is a very powerful whirlpool; a large, swirling body of water. The word is a compound of the Nordic words mala (grind) and ström (stream). It originates from a mythological story of huge masses of sea water that are continously sucked into the eye of the magical millstone "Grótti", as a result of it falling into the sea in Grottasöngr.
The original Maelstrom is the Moskstraumen, a powerful tidal current in the Lofoten Islands off the Norwegian coast