In 1994, Florida deployed seven retired M60 tanks as reefs off Pensacola; a 2000 inspection found them still in their original positions on the seafloor

The M60 tank has, for decades, very prominently represented military power on land. Built to move across battlefields, these armored vehicles were designed to survive explosions, extreme conditions, and heavy use. But by the 1990s, many had become outdated and were sitting unused. Florida found another use for them and turned them into underwater homes for marine life, finding a completely different but important purpose for them.

In 1994, workers decommissioned the M60 tanks and deployed them at several offshore locations. This was part of the implementation of the plan to create artificial reefs in the Gulf of Mexico. The project repurposed retired military equipment as artificial reef habitat that also supported recreational fishing and diving. Seven retired M60 tanks were prepared and deployed as part of Florida's REEF-EX artificial reef demonstration across Escambia, Okaloosa, and Bay counties. The tanks were cleared and brought to readiness for their underwater use.

How old tanks became part of the ocean floor


The decision to use tanks as reefs came from a practical problem. The U.S. military had thousands of tanks that were outmoded and no longer had a purpose in modern warfare. Rather than abandoning them all, officials wondered if the heavy steel vehicles could be used for other purposes. Artificial reefs provide a hard surface that algae, corals, invertebrates, and other marine organisms can colonize, gradually creating habitat for fish and other sea life. With time, algae and other micro-organisms and larger sea life might begin to take up occupation of these structures for protection and browsing. However, before military equipment can be placed in the ocean, adequate preparation is required.

Can a battle tank survive underwater?

The ocean creates a different set of challenges for a tank that was created to survive on land. Saltwater corrodes metal, storms displace structures, and unstable materials turn into dangers instead of habitats. The two most important experiments that had to be conducted were: did the tanks stay in position, and did they really act as reefs? Artificial reef materials must be heavy, stable, durable, and non-polluting to ensure long-term benefits in terms of reef habitat. The Florida artificial reef standards are targeted at the characteristics the materials should possess prior to placement in the water.

Stability was crucial, as an artificial reef is not simply a rock dropped in the sea. They are important because they are needed to remain in place sufficiently to allow marine life to grow around them. Six years later, an inspection of the tanks deployed revealed that they were still on the seafloor in their original positions. The tanks also exhibited a larger trend as occurred with artificial reef projects. The findings matched what has been observed at many other artificial reef sites. Heavy steel structures, ships, concrete, and other durable materials have been used in coastal waters because they provide surfaces where marine organisms can attach and where fish can find shelter.

How artificial reefs help researchers understand oceans

Marine scientists and regulators have long emphasized that reef materials must be carefully selected. Objects that break apart often spill dangerous chemicals, or fly around during a storm can cause harm to the marine environment rather than help it. That is why military tanks were not put underwater as they were built. Removing or mitigating material from the tanks was done before deployment to prevent environmental consequences in order to create a calm and controlled habitat.

Artificial reefs have been used as long-term ecosystem study sites because they allow scientists to examine how marine communities develop over time. Because marine communities develop gradually, durable reef structures allow algae, invertebrates, and fish populations to establish themselves over many years. Long-lasting materials therefore provide researchers with valuable opportunities to study how artificial reefs change over time.