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Welcome to Brainstuff, a production of IHeart Radio.

Hey, Brainstuff, Lauren Vogelbaum here.

On January 29th of 1992, a cargo ship spilled a portion of its contents into the Pacific Ocean, thus releasing some 28,000 little yellow rubber ducks and other bathtub toys to journey around the globe.

Beachcomers and other amateur and professional ocean enthusiasts logged findings of them for at least 20 years. The last report I know of is from August of 2013.

They've ridden ocean currents up the eastern coast of the United States along the shores of Greenland and through the ice pack in the Arctic Ocean.

Some 2,000 are still unaccounted for. How these simple bathtub toys remain to float for so long isn't much of a mystery.

After all, they're made of lightweight rubber and filled with air.

It's no wonder the denser seawater holds them up.

But how do their flesh-and-blood brethren accomplish the same task?

Real ducks aren't made of plastic,

and they contain more than just air. Today, let's talk about how ducks float. To understand this,

you first have to understand why anything floats. Objects either float or sink in water because of what's called buoyancy.

When an object placed in water weighs less than the amount of water that it displaces,

the object floats. If it weighs more, the object sinks. If that cargo ship had been

transporting bowling balls, you can bet they wouldn't be cruising the high seas.

Rubber ducks, however, are a different story. They typically weigh no more than, say,

0.2 ounces, but they take up about 4.5 cubic inches of space. For our metric friends,

that's about 5 grams and 75 cubic centimeters.

That means that the water that they displace weighs over 2.5 ounces, or 75 grams, so that water

significantly outweighs them. Therefore, the heavier seawater will keep them afloat. Real ducks are also lighter than the water

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