sargasso sea

from WordNet (r) 3.0 (2006)

Sargasso Sea
    n 1: a vast area of the North Atlantic from the West Indies to
         the Azores that is dense with gulfweed

from The Collaborative International Dictionary of English v.0.48

Sargasso \Sar*gas"so\, n. [Sp. sargazo seaweed.] (Bot.)
   The gulf weed. See under {Gulf}.
   [1913 Webster]

   {Sargasso Sea}, a large tract of the North Atlantic Ocean
      where sargasso in great abundance floats on the surface.
      [1913 Webster]