Smaller vessels from the U.S. Coast Guard Cutter Munro chased a self-propelled semi-submersible vessel that crew members believed was smuggling drugs under the eastern Pacific Ocean.
The sub was spotted by aircraft that radioed to the ship.
Eventually, the Coast Guard members were able to get close enough to jump on the sub and open the hatch.
Five people on board the sub were transferred to the U.S. Drug Enforcement Administration. They also found 17,000 pounds of cocaine in the vessel, CNN reported.
The Coast Guard has a difficult job trying to even find the subs in the vastness of the oceans.
"They blend in," Lt. Cmdr. Stephen Brickey told CNN. "Most of the vessel is underwater, so it's hard to pick out. They're painted blue. They match the water."
The Coast Guard nabs only about 11 percent of all drug-running subs gliding under the water in an area Brickey said is about the size of the country, CNN reported. And they have been doing the job with what Brickey compares to two police cars that are over 50 years old. But the Munro is a new vessel, Brickley told CNN.
"These sorts of capabilities on these ships is what will make us successful in the future," Brickley told CNN.