According to intelligence, Rear Adm. Nimmich said, about 20 submersibles are currently being manufactured. And at any given time, five or six are on the move up the Guatemalan or Mexican coasts, he said.
Looking out the porthole at a U.S. Coast Guard ship, left, is not an uncommon experience for smugglers. The U.S. Coast Guard along with the navies of South and Central American countries have been working together to track down these hard-to-find submersibles. (ABC News)