A Colombian drug lord dubbed “the Prince of Semi-Submersibles” was sentenced to over 20 years in prison for operating a fleet of narco-submarines that smuggled thousands of kilos cocaine into the U.S. from South America, federal prosecutors announced Monday.

Narco-submarines are makeshift nautical vehicles painted in ocean colors that have one purpose: to smuggle narcotics in hermetically sealed containers across thousands of miles of ocean to illicit ports of call in other countries. The technology has progressed in recent years and has become a significant force in the international drug trade.

Oscar Adriano Quintero Rengifo, 35, also known as “Guatala,” was sentenced to 20 years and 10 months in federal prison for smuggling cocaine in narco-subs, the U.S. Attorney’s Office for the Middle District of Florida said in court papers.

Quintero Rengifo was part of a transnational criminal organization that smuggled cocaine from South America to Central America for ultimate importation into the United States, according to a federal plea agreement. The organization primarily sent self-propelled semi-submersible vessels to Guatemala, where the cocaine was then smuggled over the Guatemala and Mexican borders, and then into the U.S., prosecutors said.

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A statement by federal prosecutors described Quintero Rengifo as “the Prince of Semi-Submersibles,” a term originally coined for him by media in Colombia. Quintero Rengifo rose through the ranks of a Colombian-Guatemalan drug organization to become an expert international smuggler.

“The organization primarily sent vessels such as self-propelled semi-submersible vessels to Guatemala, where the cocaine was then smuggled over the Guatemala/Mexican border and then into the United States,” court documents said. “A former mayor in Guatemala, who controlled drug routes in northern Guatemala into Mexico, oversaw the smuggling of cocaine to Mexican cartel members. Quintero Rengifo progressed within the group, from organizing smuggling operations, to ultimately investing in shipments and securing investors.”