Drop a bottle in the sea and see where the currents take it.
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Someone drops a plastic bottle in the sea off California. Nobody steers it, and it has no engine. Where does it end up? Back on a beach? Across the ocean? The streaks show how the water moves.
Winds push the top of the sea. Together with the spin of the Earth, they turn the water into giant, slow whirlpools called gyres. This one goes clockwise. Anything that floats gets carried round and round with the currents.
Pick where to drop it, then follow the white streak. It goes round the gyre, and each lap it drifts a little closer to the middle. The path is simplified: a real bottle wanders, and could take years.
A bottle dropped off Britain follows the North Atlantic Gyre: south past Spain and Africa, west along the tropics, then north up the Gulf Stream. This is the same loop as in the Gulf Stream lesson. It also ends up in the calm middle.
People imagine a floating island of rubbish. It isn’t one. A garbage patch is more like a thin soup of small pieces, many too small to see, spread over a huge area. You can’t walk on it, and you can’t see it from space. The picture is simplified, and the edges of a patch move.
Floating rubbish drifts to the calm middle of a gyre.
🌍 Play this lesson on the globe
The globe pictures are simplified to show the idea. Earth images: NASA Blue Marble (public domain).