The Sargasso Sea is a region in the central North Atlantic Ocean surrounded by four ocean currents: the Gulf Stream on the west; the North Atlantic Current on the north; the Canary Current on the east; and the North Atlantic Equatorial Current on the south. The central region has no steady currents of its own and is basically a relatively calm body of water in an otherwise active ocean. Its most prominent ecological feature is the seaweed Sargassum, from which its popular name is derived. Its eastern edges were discovered by Portuguese sailors in the 15th century, and it was crossed by Christopher Columbus during his voyages to the New World. Legends arose of sailing ships becalmed in the Sargasso Sea and becoming entangled in the seaweed, with the sailors on board dying from lack of food and water, but there is no evidence to support those stories. More recently, it has been determined that the Sargasso Sea is the common home of the American and European eels. Both species migrate to the Sargasso Sea to lay eggs. The larva then swim to their respective ecosystems to grow, mature, and continue the cycle. Loggerhead turtles utilize the Sargasso Sea in a reverse manner. They are born on sandy beaches of the Atlantic and associated waters. The turtles then swim to the Sargasso Sea to grow and mature. Recent studies by J. Craig Venter and others have revealed a wide variety of life forms (particularly microscopic) in the Sargasso Sea. As the center of a constantly swirling vortex, the Sargasso Sea naturally accumulates floating debris, with non-biodegradable plastic waste becoming increasingly prevalent – somewhat similar to the so-called Great Pacific Garbage Patch, but not yet as severe.