The US Coast Guard has seized 16,000 pounds of cocaine worth $181 million, the largest seizure of its kind in Coast Guard history.

The Northern California coast guard seized the cocaine from a semi-submersible vessel in the Pacific Ocean, 200 miles south of Mexico on July 18.

Approximately, 4,000 pounds of the drug sank during the seizure, the agency reported.

The agency also arrested four suspected smugglers from Colombia and seized 275 bales from the vessel.

"Our success intercepting this drug-laden, self-propelled semi-submersible is a testament to the collaboration of our partner agencies, and demonstrates the importance of our increased presence in the Western Hemisphere," said Vice Adm. Charles W. Ray, commander, Pacific Area.

"Every interception of these semi-submersibles disrupts transnational organized crime networks and helps increase security and stability in the Western Hemisphere."

The force has also thwarted 15 different drug smuggling attempts since April and have seized over 33,000 pounds of cocaine valued at more than $540 million since May 2015.

Almost 80 percent of drugs, which were smuggled into the US in 2012, were transported through maritime routes and nearly 30 percent of the drugs smuggled by sea come from narco submarines.