Watch: Submarine Carrying 8 Tons of Cocaine Seized by Coast Guard

August 10, 2015 Last Updated: August 10, 2015

The U.S. Coast Guard noticed something strange over waters off the coast of El Salvador: A submarine. But it wasn’t an ordinary sub, it was a so-called “narco-submarine,” which had 16,000 pounds of cocaine stashed inside worth about a quarter of a billion dollars.

It went down on July 18, but this week, the Coast Guard released footage of the bust.

The Coast Guard tried to tow the vessel back to the port, but it sank to the bottom of the seabed. Another two tons–about $45 million worth–of cocaine also sank. The Coast Guard pulled 12,000 pounds out of the homemade vessel, which was about 40 feet in length.

Over the past decade or so, submarines have become a lucrative way to smuggle drugs from Central America into the U.S.

According to a 2012 New York Times article on narco-subs, cartels “used container ships and fishing vessels and go-fast boats and submarines — crude semi-submersibles at first, then fully submersible subs, conceived by engineers and constructed under the canopy of the Amazon, then floated downriver in pieces and assembled at the coastline.”

The submarines can cost in excess of $1 million, “but to the smugglers, they are effectively disposable,” the report stated.

If the Coast Guard catches it, a worker on the submarine can pull a lever that floods the interior so the evidence sinks, leaving the crew in the water. That’s what may have happened last month.