The Mexican Navy said Tuesday it has seized 3.6 tons (about 8,000 pounds) of cocaine aboard a “narco sub” off the Pacific coast which was spotted earlier this week about 153 miles off the resort of Acapulco.

Navy ships arrived to intercept the boat, which was carrying 102 packages filled with bricks of cocaine, authorities said in a news release.

The craft, of a type known as “go-fast boats,” was powered by two outboard motors and appeared to be a low-profile, semi-submersible craft — commonly known as a “narco sub” — designed to make detection more difficult.

Aboard the craft, the Navy detained nine crew members, six of whom were foreigners. The Navy did not specify their nationalities, but many of the boats found off Mexico have Colombian or Venezuelan crew members.

Officials released an image of numbered packages containing the cocaine flanked by two naval ships.

Cocaine is produced in South America and is usually shipped through the Pacific or the Caribbean to reach the U.S. market.

The seizure comes just weeks after the Mexican navy announced it had seized more than 8.3 tons of drugs in the Pacific Ocean, a record for a single operation at sea. The cargo was intercepted from six different vessels, including a “narco sub” that held about 4,800 pounds of narcotics.

The Navy said Tuesday that more than 15,000 kilograms of alleged drugs have been seized at sea under the current administration.

Earlier this year, Mexico’s Navy seized more than seven tons of suspected cocaine in two separate raids in the Pacific Ocean, and dramatic video captured the high-speed chases on the open sea.

In September, the U.S. Coast Guard said that it had offloaded more than $54 million worth of cocaine  — including over 1,200 pounds of drugs that were seized from a “narco sub.”

Semi-submersibles, which cannot go fully underwater, are popular among international drug traffickers as they can sometimes elude detection by law enforcement. The vessels are sometimes seized in Colombian waters while heading to the United States, Central America and Europe. Earlier this summer, the Colombian Navy said it seized two “narco subs” off the country’s Pacific coast that together contained almost 5 tons of cocaine.