Amanda Macias/Business Insider
23 July 2015

In a joint operation, the US Navy, US Coast Guard, and assets from the Customs and Border Protection Office of Air and Marine, intercepted a "narco-submarine" filled with more than 16,870 pounds of cocaine off the coast of El Salvador.
On July 18, a Coast Guard cutter commandeered a self-propelled, semisubmersible vessel carrying 274 bales of cocaine weighing more than eight tons, according to a press release from US Customs and Border Patrol.
The four individuals found with the illicit contraband were detained by US authorities.
Similar to a submarine, "narco-subs" are custom-built vessels used by traffickers to move large amounts of drugs. The first narco-sub was detected in 1993 and was built from wood and fiberglass, could not submerge, and could only travel at 10 mph.
narco submarine
US Customs and Border PatrolUS authorities sit on a "narco-submarine" found off the coast of El Salvador.