Submerged in the Atlantic Ocean off the coast of Spain and Portugal are giant, salty whirlpools of warm water. These deep-water whirlpools are part of the ocean’s circulatory system, and they help drive the ocean currents that moderate Earth’s climate. Warm water ordinarily sits at the ocean’s surface, but the warm water flowing out of the Mediterranean Sea is so salty (and therefore dense) that when it enters the Atlantic Ocean at the Strait of Gibraltar, it sinks to depths of more than 1,000 meters (one-half mile) along the continental shelf. This underwater river then separates into clockwise-flowing eddies that may continue to spin westward for more than two years, often coalescing with other eddies to form giant, salty whirlpools that may stretch for hundreds of miles. Because the eddies originate from the Mediterranean Sea, scientists call them “Meddies.”
Published Mar 23, 2006
Some of the smallest organisms on our planet can be viewed from space: MODIS on NASA’s Aqua satellite captured this image of a plankton or bacterial bloom south of Fiji on October 18, 2010.
Published Nov 13, 2010
Freshened surface water and abundant nutrients lead to an explosion of algae in the inland sea.
Published May 31, 2015
Along the northeastern coast of Greenland, glaciers and ocean currents sometimes produce an eye-catching display of shapes and colors.
Published Aug 10, 2006
A colorful mixture of dissolved organic matter and sediments help trace the sea’s otherwise invisible currents and eddies.
Published Oct 13, 2020
A Korean satellite provides an hourly view of the phytoplankton in the ocean, while also offering a testbed for future ocean-observing satellite missions.
Published Jun 21, 2016
Swirling waters from the Agulhas Current stir up a phytoplankton bloom.
Published Feb 11, 2012
A colorful image of the Arabian Sea shows the various types of activities occurring in the waters.
Published Dec 27, 2018
Phytoplankton and stirred up sediments deliver a splash of spring color to the Black Sea.
Published May 13, 2016
A patch of open water made a rare appearance amid winter sea ice in the Weddell Sea near Antarctica.
Published Sep 1, 2016
Phytoplankton, sediment, and dissolved organic matter all likely contributed to the green colors of the North Sea in late October 2011.
Published Nov 6, 2011
A hazy plume drifted over the northern end of the Caspian Sea in early April 2008. The translucent plume swirling over the water contrasts with the nearby opaque white clouds. The plume might result partly from smoke from springtime agricultural fires in farmland north of the sea.
Published Apr 16, 2008
