As part of the Joint Patrol Treaty with the United States, the U.S. Coast Guard led an anti-drug operation that resulted in the arrest of three individuals for trafficking almost two tons of cocaine in a narco-submarine.

A narco-submarine is a type of custom ocean-going, self-propelled, semi-submersible vessel built for drug smugglers.

According to the Ministry of Public Security, the case began on Sunday when a U.S. Coast Guard plane spotted a suspicious submarine, crossing the Costa Rica Pacific Coast with no visible registration plate number or country flag.

U.S. officials instructed the Costa Rican Coast Guard to follow the alert's coordinates to intercept the 45-foot-long submarine around 69 nautical miles off Matapalo Cape in Osa Peninsula, Puntarenas Province.

This is the first case of a narco submarine interception in Costa Rica this year. Inside the submarine, the officers found many packages containing drugs along with large fuel containers and navigation equipment.

Officers arrested three male crew members, one from Ecuador surnamed Castillo (29), and two from Colombia surnamed Parades (47) and surnamed Lopez (37).

Police towed the submarine to the Golfito Beach Coast Guard Station.

At the place on Monday, specialists from the Drug Control Police conducted a more thorough inspection and found almost 2,000 cocaine packages, each weighing approximately one kilogram.

The submarine, drugs, fuel and electronic navigation equipment were confiscated as evidence in this case.

The suspects were taken to the cells of the Puntarenas Public Ministry, where they had to wait for a judge to order pre-trial prison indicted of the alleged crime of international drug trafficking.

Authorities call for people to report any suspicion of drug sales or trafficking to the ten-digit confidential line 800-8000-645 or fast line 11-76, where bilingual agents can answer calls in English or Spanish.

So far this year Costa Rica seized almost 15 tons of cocaine and about 10 tons of marijuana, authorities added.