Answer: Old Tires

There are more than a few reasons why governments around the world have experimented with creating artificial reefs. There’s an interest in repairing existing natural reefs that have been damaged by storms or catastrophic die-offs in the face of human interference. Fish aren’t picky if the reef they live in, or near, is natural or man-made. Artificial reefs can help boost tourism by giving hobby divers somewhere to explore, and help the recreational and commercial fishing industries by providing fish somewhere to live.

What better way to build a reef than to use stuff that we already have, but need to get rid of, right? In that regard, there have been some extremely fantastic efforts around the world to use old ships, subway cars, tanks, and other large metal structures in the creation of artificial reefs. The vehicles are cleaned well, stripped of harmful materials like old oil or fuel, and sunk in long piles to create perfect places for a wide variety of fish and marine creatures to live. An aircraft carrier is pretty spacious for a bunch of humans, after all, but incredibly palatial for fish.

Alas, not all artificial reef efforts have been successful. In the 1970s, tens of thousands of tires, bound together by nylon and steel cabling or clips, were sunk into the coastal waters of the Northeastern United States and, later, Florida in an effort to create new reefs. The largest such experiment was the Osborne Reef, located off the coast of Fort Lauderdale. The original reef project was based on using large concrete jack-like-shapes to create the basic structure for a natural reef to take shape, but was radically expanded with the introduction of roughly two million tires.

Other countries around the world tried similar experiments in the early 1980s. The results were, well, about as great as you’d expect them to be from dumping acres worth of tires into the ocean. It didn’t take long for the cabling and clips to rust or rot through, and tropical storms pushed the tires around, spreading them out and even slamming them into nearby living reefs and damaging them. Divers today report that the areas with the tires are almost completely devoid of life.