Sargasso Sea (särgăsˈō) [key], part of the N Atlantic Ocean, lying roughly between the West Indies and the Azores and from about lat. 20°N to lat. 35°N, in the horse latitudes. The relatively still sea is the center of a great swirl of ocean currents and is a rich field for the marine biologist. It is noted for the abundance of gulfweed (see seaweed) on its surface. The Bermuda islands are in the northwestern part of the sea.