As the use of drug laden submersibles creeps up the coastline of South America, these craft finally came into the range of the Mexican Navy (they have a Navy? – sorry – I digress). After Columbian authorities captured or sunk about 8 or 9 of these semi submersibles loaded with drugs – one wandered into Mexican waters and got captured. Mexico’s navy seized a homemade submarine carrying a drug shipment off the Pacific coast on Wednesday and arrested its four-man crew. The seizure is a first for Mexico.

The 30-foot makeshift submarine was detected heading north about 200 miles off the southern state of Oaxaca, representatives reported. The green-topped, arrowhead-shaped vessel was intercepted when it surfaced hours after being detected, and the crew was taken into custody without resistance.

The suspects were flown by helicopter to the city of Huatulco, where they told reporters they left the Colombian coastal town of Buenaventura a week ago. The crew members said they were fishermen forced to make the journey by drug traffickers who threatened to harm their families.

“We didn’t know what was on board because we never saw it. It was sealed,” said one of the four, Jose Felix Enriquez. The navy said in a statement that the sub was apparently packed with cocaine, but authorities were still determining how much was on board. The capture has been reported as was worthy of an action thriller: elite Mexican troops rappelling from a helicopter onto the deck of a mysterious submarine.

The 33-foot vessel turned out to be crammed with parcels believed to contain cocaine, possibly tons. Its disheveled crew of four emerged in stocking feet and baggy shorts, saying they had shipped out from Colombia a week earlier under threat of death.

Capt. Jose Luis Vergara, a spokesman for the Mexican navy, said authorities were hauling the “very well-constructed” vessel to shore and had yet to weigh the contraband, which he said likely amounted to “tons.”

U.S. officials say the craft are being used more often because they are more difficult to detect by radar. The seizures represent a fraction of the 40 or so that have been spotted since 2007, according to U.S. authorities. “When they think they might be caught, the crews tend to scuttle them,” said Jose Ruiz, spokesman for the U.S. Southern Command in Miami, which monitors drug activities. “They get out of them, sink them, and the drugs go to the bottom of the ocean so they can’t be recovered for evidence.”

Wednesday’s seizure of the olive-green, surfboard-shaped vessel in the Pacific Ocean about 125 miles from the southern Mexican state of Oaxaca, was the first off the coast of Mexico, authorities said.

In a statement, the Mexican navy said its forces moved in on the vessel after receiving intelligence from “national and international agencies.” Of course since this happened closer to the USA, the Mexican authorities couldn’t have pulled this capture off by themselves – U.S. Homeland Security Secretary Michael Chertoff said Friday that U.S. intelligence led Mexican forces to a small submarine captured this week packed with 5.8 tons of cocaine.

Chertoff called the vessel’s seizure Wednesday off Oaxaca state in southern Mexico “a great example of our cooperation.” “We shared information with the Mexican navy, but the Mexican navy acted alone in actually executing the seizure,” Chertoff told a news conference in Mexico City.