The South Carolina National Guard has found a good use for old M60 tanks and M113 armored personnel carriers.

Every year, the Guard and the state Department of Natural Resources drop old armored vehicles into the ocean to form artificial reefs that in turn draw sea life, fishermen, scuba divers and tourists to South Carolina.

"There's not another project like it," said 1st Lt. Jason Dunnagan, the Innovative Readiness Training Project coordinator for the South Carolina Guard. "It's being part of something that's going to last longer than you digging a hole on Fort Jackson and at the end of it saying 'task done.' "

This partnership between the South Carolina Guard and the Department of Natural Resources began 17 years ago with the goal of developing and improving sea life off the coast of South Carolina.

Since then, the Guard has worked with the DNR to put vehicles into the ocean once a year.

On Sept. 4, the Guard dropped 36 vehicles — all of them in the M113 family — into the water off the coast of Beaufort, South Carolina.

In all, the partnership has placed 587 armored vehicles, 248 shipping containers and 35,000 tons of concrete at the bottom of the ocean off the state's coast, creating more than 1.1 million cubic feet of new reef habitat, according to data from Dunnagan.

"It's a cool project," he said, adding that the artificial reefs bring in $83 million in tourism money — hotel revenue, deep sea activities, and so on — to the state every year.

In addition, the reefs can remain productive for 150 years, according to information from the South Carolina Guard.

"It won't be long before these recently dropped vehicles will be covered with long puffs of soft corals, sea sponges and barnacles and used by a variety of fish to provide food and protection," said Robert Martore, who works with the DNR, in a statement.

Officials also said the vehicles, after being stripped and demilitarized, are safe to drop into the water with no negative environmental impact.

The annual event, called Reef-Ex by the Guard, allows troops to receive much-needed training while giving back to their local community, Dunnagan said.

"There's excess equipment in all your Army depots, and they're not going anywhere," he said. "If it was obsolete in 1990, it's obsolete in 2014."

For Reef-Ex, the Guard seeks vehicles in the M60 and M113 families, including World War II and Vietnam era combat engineer vehicles, tanks and personnel carriers.

The Guard works with the Defense Logistics Agency to acquire the vehicles each year, Dunnagan said. On average, the Guard provides 30 to 60 vehicles each year.

"We demilitarize them to the Army standard, and we transport them down to the coast," he said.

The Guard then loads the vehicles onto a barge, which the DNR then takes out to South Carolina's prescribed reef locations, Dunnagan said.

About 200 soldiers, from transportation troops and engineers to maintenance soldiers, participate in the exercise every year, Dunnagan said. This year, soldiers from the DC Guard participated alongside South Carolina Guardsmen.

"It develops relationships with other states," Dunnagan said.

Reef-Ex is a big deal in South Carolina — for both the Guard and the state, which is willing to pay for the vehicles because of the revenue artificial reefs bring to the economy, Dunnagan said.

"When we're not overseas, we're giving back to the community," he said. "There's not an Army base or Air Force or Navy base in every town, but there's a National Guard armory in almost every town across the nation. This is a way for us to reach out and help."