The U.S. Coast Guard said Tuesday that it had seized a 40-foot semi-submersible in the Eastern Pacific Ocean that was carrying 12,000 pounds of cocaine worth more than $165 million earlier this month.

The crew of the Florida-based cutter Valiant was directed to intercept the "narco sub" after it was detected and monitored by a patrol aircraft, the Coast Guard in a statement Tuesday.

COAST GUARD SEIZES MORE THAN 12,000 POUNDS OF COCAINE

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Two small boats with boarding teams were launched from the Valiant to take down the sub in the early morning with assistance from Colombian naval assets. Four suspected drug smugglers were also apprehended.

The exact location of where the boat was intercepted was not revealed.

"There are no words to describe the feeling Valiant crew is experiencing right now,” said Cmdr. Matthew Waldron, Valiant’s Commanding Officer.

U.S. Coast Guard boarding team members climb aboard the suspected smuggling vessel (Photo by Petty Officer 1st Class Luke Clayton)

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"In a 24-hour period, the crew both crossed the equator and intercepted a drug-laden self-propelled semi-submersible vessel," he added. "Each in and of themselves is momentous events in any cutterman's career. Taken together, however, it is truly remarkably unprecedented."

The Coast Guard offloaded more than 1,000 pounds of cocaine but left the rest due to concerns about the vessel's stability. More than 12,000 pounds of cocaine was recently seized by the Coast Guard in interdictions of suspected drug-smuggling vessels off the western coasts of Mexico, Central America and South America.

Fox News reporter Melissa Leon contributed to this report.