How Ocean Currents and Gyres Disperse Objects Across the Globe: The Journey of Rubber Ducks
Discover how ocean currents and gyres transport objects across the world’s oceans, including the famous journey of 29,000 rubber ducks that traveled from the Pacific to shores around the globe. Learn about the environmental impact and the science behind these powerful oceanic forces.
The Journey of Seeds and Objects Across Oceans
How do seeds from vines in Mexico end up in Norway, or Japanese fishing floats find their way to Alaska? The same way 29,000 bathtub toys that escaped their containers during a storm in the North Pacific in 1992 were washed up almost 2,500 miles away on the shores of southwestern Alaska ten months later. The short answer is they were transported by currents, held by giant eddies called gyres, and finally released into other currents.
Understanding Ocean Currents
Ocean currents flow in complex patterns influenced by wind, water density, salinity, solar heating near the equator, the topography of the ocean floor, and the rotation of the earth. These currents are relatively constant and flow in one direction, in contrast to tidal currents closer to shore. Surface currents are generally wind-driven, while deep ocean currents are driven by other factors.
The Role of Wind and Sun
Wind causes large surface currents that flow year-round. At the equator, the direct rays of the sun cause intense heating. As the hot air rises, it leaves areas of low pressure. Warm air from the equator begins to cool and sink about 30 degrees north and south of the equator. The air movements toward the equator are called trade winds: warm, steady breezes that blow almost continuously. The rotation of the earth also affects the currents through the Coriolis force, causing water to move to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
Thermohaline Circulation: The Global Conveyor Belts
The sun also alters the density of the ocean surface water by changing its temperature and salinity. If water cools or becomes saltier through evaporation, it becomes denser, setting up density-dependent currents known as thermohaline circulation. These ocean currents, often called ‘global conveyor belts,’ flow under the surface of the ocean, moving water across vast distances over long periods.
Gyres: The Ocean’s Rotating Eddies
Currents help transfer oxygen from the atmosphere into the deep ocean, mix nutrients, and even transport trash. However, they also form large ocean eddies known as gyres. A gyre is a large system of rotating ocean currents formed by surface winds, the movement of the earth, and land masses. The major gyres of the earth’s oceans are named for their locations: North Atlantic, South Atlantic, North Pacific, South Pacific, and Indian Ocean gyres.
The Size and Impact of Gyres
Gyres are enormous—comparable to the size of continents—and can trap objects for years. For example, the North Atlantic gyre is 1,200 x 3,000 nautical miles, with an 8,000 nautical mile circumference. The orbital period is 3.3 years, but only half of the objects in the giant gyre will escape in each full revolution. This means there’s a one percent chance that a given object could remain adrift after seven orbits—approximately 23 years.
The Tale of the Tub Toys
On January 10, 1992, a ship sailing from Hong Kong lost a container overboard, releasing 29,000 bath toys into the ocean. Caught in the North Pacific Gyre, these toys, including rubber ducks, began washing up on the shores of Alaska ten months later. By 2005, some toys had reached beaches in eastern North America between Maine and Massachusetts. In 2007, the first tub toys were found on beaches in England.
Environmental Impact: Trash in the Gyres
It’s not just rubber ducks that get caught in gyres. Trash enters coastal currents and is fed into the gyres, creating huge floating islands of garbage. The North Pacific gyre is often called the “garbage patch,” a mass of plastic and other debris that resists decomposition. Dead birds can be found with bellies full of plastic debris.
Exploring Ocean Currents and Gyres
The American National Aeronautics and Space Administration (NASA) has developed a visual tool to see and predict currents. The program, called OSCURS (Ocean Surface Current Simulator), can be found at: Ocean Surface Currents Simulator.
Further Reading and Resources
For more detailed information on the history of the tub toys, visit:
To learn more about ocean trash and gyres, explore:
- Great Garbage Patch
- 5 Gyres Institute
- EarthSky on the Pacific Garbage Patch
Devi Sharp has written for ALL AT SEA since 2008.
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