A navy helicopter spotted the craft while on patrol over the Gulf of Guayaquil. Upon realizing they had been seen, the crew abandoned the semi-submersible and sank it before authorities came, swimming to the safety of two nearby fishing boats.

The Coast Guard intercepted the fishing boats, arresting three Colombians and one Ecuadorian on drug trafficking charges.

Though they were unable to recover the narco-sub, an unnamed official told the Associated Press that it was 13 meters long and 3 wide, and had the capacity to hold up to 8 tons of cargo. It is not known whether it was carrying drugs when it was sunk.

InSight Crime Analysis

This is not the first time that Ecuadorian officials have intercepted a narco-sub. In July 2010 security forces found the first fully-operational, completely submersible smuggling craft in a makeshift shipyard along the Pacific. At 100 feet long and equipped with a periscope, the find was labeled a "game-changer” by counternarcotics officials because of its ability to travel to the US from South America with a low likelihood of being detected.

As InSight Crime has reported, security crackdowns throughout the region have made drug traffickers increasingly reliant on such homemade underwater vessels, which are becoming more and more sophisticated. According to a 2010 report released by the United Nations International Narcotics Control Board (INCB), the use of semi-submersibles has "strongly increased" over the past several years. The INCB cites official Colombian figures which indicate that only 19 were seized worldwide from 1993 and 2007, but 34 were seized in 2008 and 2009 alone.