The Collaborative International Dictionary of English v.0.48:

Maelstrom \Mael"strom\, n. [Norw., a whirlpool.]
   1. A celebrated whirlpool on the coast of Norway. Hence: any
      large or powerful whirlpool.

   Syn: whirlpool, vortex.
        [1913 Webster]

   2. Also (Fig.) An uncontrollable agitated or confusedly
      disordered state or situation; as, a maelstrom of vice.
      [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

maelstrom
    n 1: a powerful circular current of water (usually the result of
         conflicting tides) [syn: whirlpool, vortex,
         maelstrom]