The Sargasso Sea is a motionless sea confined to the sub-tropical north Atlantic gyre. The area of the sea is found between 20 degrees N and 35 degrees N latitude and 30 degrees W and 75 degrees W longitude—the hump extending northward of BERMUDA. The sea area which is some 700 miles wide, 2000 miles long and located in the North Atlantic, has no shores. It is bounded by ocean currents on all sides. It is located entirely within the Atlantic Ocean, is the only sea without a land boundary.

Body:

Features:

•  To its west is the Gulf Stream Current, on its east is the Canary Current, northern side is bounded by North Atlantic Current, and the south by North Atlantic Equatorial Current.
• The island of Bermuda is located on its western fringes.
• With such ocean currents on all sides, this sea area unlike the harsh cold North Atlantic, is strangely warm with stable weather conditions and with calm and weak winds.
• Another strange phenomenon which is nowhere seen in the world is, this vast water area is covered with some dense seaweed which forms a thick mat on the surface.
• This free floating golden-brown seaweed is known as Sargassum and therefore such name of the sea.

Reasons for its formation: 

• The gyral system formed by the anti-cyclonic circulation of the North Equatorial current, the Gulf Stream and the Canary current confining the water from the rest of the ocean.
• Atmospheric stability due to it being located in the transition zone of the trade winds and the westerlies which is characterized by anti-cyclonic conditions. Hence there are feeble winds which allow little intermixing with waters outside the gyre.
• The less extensive nature of the North Atlantic Ocean between 20°N-40°N than other oceans in the same latitudes.
• The higher velocity of the North Equatorial Current and the Gulf Stream create calm waters in the confined region.

The factors for it being a region with one of the highest ocean salinity:

• The atmospheric temperature in this part of the Atlantic is higher—about 78 degrees F (26 degrees C), which helps in the process of evaporation.
• The higher salinity of Sargasso Sea is attributed to high temperature and greater evaporation and lack of mixture of fresh water by rivers or ice water.

Conclusion:

Sargassum provides a home to an amazing variety of marine species. Turtles use sargassum mats as nurseries where hatchlings have food and shelter. Sargassum also provides essential habitat for shrimp, crab, fish, and other marine species that have adapted specifically to this floating algae. The Sargasso Sea is a spawning site for threatened and endangered eels, as well as white marlin, porbeagle shark, and dolphinfish. Humpback whales annually migrate through the Sargasso Sea. Commercial fish, such as tuna, and birds also migrate through the Sargasso Sea and depend on it for food.