(CBS News) CHARLESTON, S.C. - Under a shed is Bigfoot Two -- a 60-foot semi-submarine captured by the U.S. Coast Guard in the Caribbean in 2008. It cost just $2 million to build but was carrying $150 million in cocaine.
Vessels like that one are called semi-submersibles because they sail with their tops just above the surface to maintain an air supply for the crew. The semis move cocaine from Colombia to Central America, where it's then transferred by land into the U.S.
Inside we found the semi-sub to be a floating warehouse with a huge space for drugs and little else. In the pilot house of the Bigfoot Two semi-submersible are the helm, a compass, the controls, and very cramped quarters for the crew of four.
Another semi-sub was caught by the Coast Guard in September, 2011. While patrolling drug-smuggling lanes, the cutter Mohawk received an intelligence tip and intercepted a vessel near Honduras. When a Coast Guard skiff closed in, the crew scuttled the sub and bailed. The vessel sank in seconds.
With an unknown cache of cocaine resting just 80 feet below the surface, the Coast Guard feared dealers would try to retrieve the lost treasure. So the FBI's dive team was called.
"Part of the whole mission is to deny those drugs the ability to get here to our country," said dive team leader Michael Tyms, "so to leave them there would've left the job unfinished, so to speak."
Wearing underwater cameras, Tyms and his team cut into the submarine, finding more $200 million worth of cocaine wrapped in waterproof packets.
Now drug runners are moving to a more sophisticated harder-to-detect vessel. Soldiers in Ecuador have discovered some fully submersible submarines along rivers that connect to the sea.
Coast Guard Commander Tom Walsh worries about other groups getting access to that kind of stealth technology. Asked if someone could use a submersible for terrorist activity or arms running, he said: "That's a very big concern of ours. These vessels would certainly be of value to terrorist organizations that want to move people or equipment or other items towards the United States."
As for the men who jumped off that semi-sub, they were rescued by the Coast Guard and are now in prison in the United States.