Imagine the future undersea explorers coming across these and trying to make sense of them…
The tourism boards of east-coast states buy a boatload of the cars from New York's transit authority. Once they're stripped of their doors, windows, wheels and interiors, a barge filled with 30 to 40 cars chugs down the coast, and a metal crane, er, shoves them them into the sea.
On the sea floor, the cars are colonised by plants and animals, and, like natural reefs, encourage communities to grow. Over the past ten years, the Artificial Reef Project has dropped around 2,500 New York subway cars into the ocean.
Full story: CityMetric