Colombia's navy seized a submarine that may have been used by drug traffickers to haul over 4 tons of cocaine for transshipment to the United States.

The 18-meter-long vessel, made of fiberglass, was discovered at sea on Thursday some 45 km from the Pacific Coast port of Buenaventura, said Adm. Guillermo Barrera, the navy's chief of operations.

Three people were arrested and two speedboats seized in the operation, but no drug was found.

Adm. Barrera said the submarine brought drug shipments to the middle of the Pacific Ocean, where they would be received by speedboats bound for Central America, and then dispatched to the U.S. by land.

Drug trafficking by sea has been rampant recent years, as a wide application of radar system has made it hard to smuggle drug by land and air.

Source: Xinhua