Colombia's navy seized a 20-meter (65-foot) submarine that likely was used to haul tons of cocaine on part of its journey to the United States, officials said Tuesday, according toAP. No drugs were found or arrests made when the fiberglass submarine was discovered Sunday in a swampy mangrove about 10 kilometers (6 miles) off the northernmost point of Colombia's Caribbean coast. The blue-colored, diesel-powered vessel had sophisticated communications systems and was capable of carrying up to 10 metric tons (11 tons) of cocaine, Rear Admiral Roberto Garcia Marquez, head of the navy's Caribbean fleet, told The Associated Press on Tuesday. Colombia is the world's largest producer of cocaine and the country's drug cartels have been known to use homemade submarines to smuggle large amounts of cocaine past U.S. and Colombian patrol boats to Central America, a stop on the route to the United States. Almost a dozen drug submarines have been found in recent years, most believed to depart from Colombia's Pacific Coast, closer to the operating base of the Norte del Valle cartel, the country's largest drug smuggling organization. Garcia Marquez said the latest discovery was the first in the arid Guajira peninsula, a region that has long been a smuggler's paradise owing to its irregular coastline next to Venezuela and a stone's throw away from several Caribbean island nations. In November, naval authorities in Costa Rica found a 15-meter-long (49-foot) submarine packed with 3 metric tons (3.3 tons) of cocaine off the country's Pacific coastline in international waters. Colombian authorities say smuggling cocaine by sea has become the top method of transport in recent years, as radar systems have made it more difficult to smuggle drugs in small airplanes without being detected.