In 2023, Georgia sank two retired Atlanta commuter trains; seven months later, divers found corals, fish, and other marine life colonizing the railcars

On July 30, 2024, divers from the Georgia Department of Natural Resources' Coastal Resources Division went underwater to check on two old train cars from Atlanta, according to a DNR release published that August. The two train cars were sunk off the coast of Georgia seven months earlier. However, what they saw surprised them. Soft coral was beginning to grow, and the wreck was home to nine species of game fish. A subway car designed for commuters was slowly becoming habitat for marine life.

From rush hour to reef floor

These cars belong to MARTA, Atlanta's transit system. Stripped down for deployment, each car weighs about 55,000 pounds. In fall 2023, MARTA retired two of its railcars, and crews spent weeks stripping hazardous materials from them before the U.S. Coast Guard signed off on the cars for deployment. Only after this process was completed were the railcars taken by barge out to sea.


They were deployed at a site called Artificial Reef L, located approximately 23 nautical miles east of Ossabaw Island, in about 55 to 65 feet of water. This was not a random disposal site. Artificial Reef L was established in 1976 and is one of 32 offshore reefs that Georgia's Coastal Resources Division has worked for over 40 years to construct and maintain. The reef itself covers about two square miles of seafloor.

What divers found seven months later

Cameron Brinton, a marine biologist with the Coastal Resources Division, said in the agency's release that the artificial reef was in good condition and that they were encouraged by the amount of coral growth and marine wildlife activity. One railcar roof had already collapsed, expected wear that actually opens up more surface area for coral without compromising the car's interior as shelter, and the site was becoming critical habitat for sport fish and endangered sea turtles, Brinton said. The DNR says fish and sea turtles were probably the first visitors, and scuba divers and anglers are already using the new reef.

Why marine life moves in so fast

It may seem surprising to see barnacles and corals on subway cars after only a few months. However, this is often how ocean colonization begins. A 2020 study in the ICES Journal of Marine Science monitored the rate of colonization of human-made surfaces left bare underwater. The study notes that as soon as a hard surface is immersed, a microbial film forms almost immediately, followed shortly by small invertebrates and other marine growth. The researchers also found that this community continues to change for years, so what the divers saw after seven months is probably only the beginning. Thus, the railcars were not having any trouble attracting life.

Georgia isn't the first to sink a train

This is not an isolated example by MARTA. New York City's transit authority has donated hundreds of retired subway cars since the early 2000s to help build artificial reefs along the Atlantic coast, shipped out to several states. The largest such site is off Delaware, known as the Redbird Reef. Jeffrey Tinsman, who runs the artificial reef program in Delaware, in an interview on CBC Radio, explains that the sandy bottom of the ocean off the mid-Atlantic coast does not provide natural shelter to many fish species. The retired subway cars provide just that. One species of fish that benefited from the structure was the tautog. Georgia's Coastal Resources Division notes that the state's reef sites also include other unusual material: retired U.S. Army tanks, tugboats, barges, and previous batches of New York subway cars

Do artificial reefs actually deliver results?

The question is whether dumping old machinery into the sea really helps or is just good publicity. A 2020 meta-analysis led by Avery Paxton, a NOAA-affiliated researcher, published in the journal Frontiers in Marine Science, analyzed 39 studies comparing fish life on artificial versus natural reefs. It found that the two types of reefs tend to support similar fish communities overall, though results varied by location and the material used, with some artificial reefs outperforming natural ones and others falling short. The team, however, was careful to add a caveat: results are highly dependent on a reef’s location and the materials used, so artificial reefs aren’t a guaranteed fix everyplace they are deployed.

The bigger picture

Scrapping a 55,000-pound railcar isn't simple; most of its metal, wiring, and parts have to be stripped and recycled or reused before it can go anywhere. Sending the empty shell to the ocean floor instead of a landfill gives that last piece of material a second job. It may take many years to realize the full impact, because reefs usually take many years to build up their ecosystem. However, right now, two of the commuter trains of Atlanta have found a whole new life.