Colombian military forces seized an electrical submarine that was being outfitted to smuggle more than four tons of cocaine by drug lords in that country.

Smugglers built the submarine with naval steel and designed it to run entirely on batteries. This allows drug smugglers to move while submerged. Officials called it a first of its kind, Argentina’s Infobae reported. More than 100 batteries had been outfitted into the submarine. This feature allows the crew to remain submerged during the entire voyage.

Colombian officials made the seizure in an area where the San Juan and the Baudo rivers meet. The submarine was outfitted to hold more than four tons of cocaine for drug cartels cells linked to the ELN guerrilla. After the seizure, ELN forces tried to use force to keep military forces from taking the submarine out of the river.

Officials estimated the approximate cost of the submarine to be $1.5 million. It took between five and six months to build. Smugglers designed the submarine with four fins, radar, and a navigation camera. The usage of the batteries does not produce exhaust gases making it difficult for authorities to detect, Infobae reported.

The use of submarines by Colombian drug dealers is a long standing practice to move their cocaine shipments from their labs in the jungle to other countries further north and eventually to Mexico or the United States, Breitbart News reported.

Ildefonso Ortiz is an award-winning journalist with Breitbart Texas. He co-founded the Cartel Chronicles project with Brandon Darby and Stephen K. Bannon. You can follow him on Twitter and Facebook.