Amazing Places

There Is One Sea on Earth With No Coastline

The Sargasso Sea, in the North Atlantic Ocean, is the only sea on Earth without a coastline. Really, it has absolutely no land borders. Occupying an impressive two-thirds of the Atlantic Ocean, this unique body of water is surrounded not by land as you'd expect, but by more and more water.

No Land in Sight

Unlike all other seas, the Sargasso's territory is defined not by the lands around it, but instead by four ocean currents within the Subtropical Gyre — the Gulf Stream, the North Atlantic Current, the Canary Current, and the North Atlantic equatorial current. These currents flow in a clockwise elliptical loop within the Atlantic Ocean and define the constantly changing borders of the Sargasso Sea.

Stretching more than 1,000 miles wide and 3,000 miles long (1,600 kilometers wide and 4,800 kilometers long), this vast expanse of sea gets its name from a genus of seaweed called Sargassum. Sargassum is a free-floating brown algae that's unique in the fact that instead of reproducing on the ocean floor, it reproduces vegetatively on the water surface. Pushed by the currents and the wind, the Sargassum functions as a migrating habitat for an impressive variety of marine life.

A Popular Hangout

Home not only to shrimp, crabs, and fish that have adapted to this floating algae, the Sargassum is also a nursery for turtle hatchlings and a spawning ground for endangered eels. Every year, larger species like humpback whales, sharks, and birds make their migrations through the Sargasso Sea, relying on the traveling seaweed for the easy prey that live within it.

The Sargasso Sea in the North Atlantic is bounded by the Gulf Stream on the west, the North Atlantic Current on the north, the Canary Current on the east, and the North Equatorial Current on the south.

Looking to pass through this borderless sea? Keep an eye out for the North Atlantic Garbage Patch — the unmistakable pile of trash similar to its larger cousin, the Great Pacific Garbage Patch. Trapped in the middle of the Sargasso's currents, this newly discovered garbage patch is comprised of more than 520,000 bits of trash per square mile (200,000 per square kilometer). The trash is predominantly tiny pieces of plastic, most less than a tenth the size of a paper clip, that's blown out to sea from landfills and people's litter.

At one point in time, the Sargasso Sea was nicknamed the Horse Latitudes, having a reputation for stranding sailors for weeks on end and forcing them to throw their horses overboard to lighten the load. While these early explorers feared that entanglement in the thick Sargussum was responsible, that is now known to be unfounded. Instead, the sea's characteristically calm waters and winds are to blame. So, fear not — go ahead and hitch a free ride through this fascinating "sea with no boundaries."

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For more about adventurous sailors, check out "The Outlaw Ocean: Journeys Across the Last Untamed Frontier" by Ian Urbina. The audiobook is free with an Audible trial. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Ashley Gabriel April 28, 2016

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