In 1972, Florida dumped 2 million tires into the ocean to build the world’s largest man-made reef; decades later, the military had to remove them

In 1972, a project intended to create the world's largest man-made reef took an unusual approach: about two million old tires were dumped into the Atlantic Ocean off Florida. The idea was to give marine life a new place to grow and create an artificial reef.

Instead, the experiment became an environmental problem that lasted for decades. The tires failed to develop into the thriving reef that planners had envisioned. Worse, many of them became loose and began moving across the ocean floor.