Thailand sank 25 tanks in 2010. Nine years later, 53 fish species thrived

Thailand’s retired battle tanks found an unexpected second life beneath the Gulf of Thailand. In August 2010, the army sank 25 old Chinese-made tanks off Narathiwat province, alongside 273 railroad cars and 198 scrapped garbage trucks.

The structures formed artificial reefs and new fishing grounds for communities whose catches had fallen after decades of overfishing. Local fishermen had appealed to Queen Sirikit for help, prompting the idea of placing obsolete equipment under the waves instead of simply discarding it.

Thailand had bought the tanks second-hand from China in 1987 at a discounted price. The army decommissioned them in 2004, leaving steel structures that could serve a different purpose for the fishing industry. Together with the railroad cars and trucks, they provided hard surfaces and shelter on a sandy seafloor.

Almost a decade after the sinking, researchers from Ramkhamhaeng University in Bangkok surveyed the man-made reef sites. Their study identified 53 fish species from 21 families around the tanks and nearby railroad cars. Snappers were the most diverse group, with seven species, while damselfish and wrasses each accounted for four.

The researchers also found a difference between the structures. The enclosed tanks held much larger schools of fish than the more open railroad cars. The species included commercially important snappers and the critically endangered humphead parrotfish, turning former military hardware into shelter, feeding grounds and habitat for an underwater community.