New York-based drug magazine High Times interviewed three crew members of a semi-submergible vessel carrying weekly shipments for a Colombian-based gang, who described the highly unpleasant conditions on board and the perils of the trip and volatile employers waiting at the other end.

"It's a very dangerous game and generally the domain of the desperate," said Jean Paul, a 42-year-old French born ex-naval officer who captains the vessels. After leaving the military he invested in real estate but became embroiled in debt, and was introduced to the narcosub trade through acquaintances.

Two of his runs have ended in having to abandon ship, once when the vessel sprung a leak and another when the boat was spotted by the coast guard. "It's a matter of offloading as many bales of cargo as possible and getting out," said Jean Paul, who managed to swim to the Guatemalan coast and escape law enforcement.

Being forced off the sub can actually bring some relief, said the captain, who now spends more time recruiting crew members and engineers than actually sailing himself. "Diesel fumes can kill you too, and the stench of another guy's shit for two days isn't nice either," he said. "Both are usually worse than the prospect of the boat sinking."

Once on dry land, the transportistas can face severe consequences for losing cargo. Jean Paul claimed he had seen at least ten people murdered, mostly crew members deemed incompetent or disloyal.

Jose, a Guatemalan-born 33-year-old crew member, said the financial rewards outweighed the considerable risk. A former fisherman, after several bad seasons he began working for the cartels collecting bales of drugs thrown off board by crews abandoning vessels -- a common path, he told High Times.

"Many fishing boats in the region haven't fished in years," he said. "They just collect bales, but keep their nets on deck to look legitimate."

He would like to go back to fishing but with a sick mother and four children he can't turn down the money offered by life on the subs. "There's no way I could make $1,500 for two days work any other way," he said.

High Times' last interviewee, 22-year-old Salvadoran Manuel, has been working for drug traffickers since he was a child, and credits them with saving him and many fellow countrymen from a life of poverty. "This business is very important for my people," he said. "Many of them would not have food or shelter without it."

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While the word "narcosub" may conjure up images of thrilling missions using cutting edge technology, as High Times explained, in reality "there is nothing romantic (or even high-tech) about the job." Like so many of people used by drug cartels along every link of the drug trafficking chain, exploitation and fear are par for the course. The poverty afflicting much of Latin America ensures there is never a shortage of vulnerable and/or desperate people willing to take on extreme risk or hardship in order to make some cash -- especially when the financial rewards are so much higher than what is on offer in legal lines of work. Moreover, those that would prefer to say no don't always have that choice, given the power wielded by the drug gangs -- especially in small communities.

The technology has advanced -- the first fully submersible vessel was found off the coast of Ecuador in 2010, and another was found in southwest Colombia in 2011 -- but these cost millions of dollars to make, so the typical drug smuggling submarine remains the crudely made semi-submergible. A fiberglass roof is stuck on top of a cigarette or go-fast boat, then an outer coating of lead is applied to add stability along with pipes on top to pump in air for the diesel engine, and a viewing periscope. An already small hull below deck becomes tiny once tons of cocaine, fuel, canned food and water are packed in, leaving as little as 120cm by 180cm for the crew to live for days at sea.

There is no bathroom. Given that many journeys last days, and the pipes that in theory pump out the toxic fumes emanating from the diesel, burning fuel and cocaine bales are not effective, the stench must be unbearable. The heat is stifling. "You constantly feel like you're suffocating," Gustavo Alonso, a licensed sea captain told Spiegel magazine. Alonso said he was forcibly recruited in Buenaventura, a Colombian Pacific drugs hub area where many submarines are said to be built. Other Buenaventura fishermen have told similar tales. "They said if we didn't [sail this submarine], they were going to kill our families," Rafael Jimenez Biojo told Semana magazine in 2008.

Despite the rudimentary design of the typical semi-submersible, they remain a very effective way to move large quantities of drugs over long distances, a fact evidenced by the steady increase in their use. By 2008, US officials estimated that around a third of all cocaine being sent from Latin America to the US was transported by subs. In 2011 maritime interdiction missions seized 129 tons of cocaine on its way to the United States -- more than five times the amount seized within the United States itself. A dramatic spike in submersibles use was also reported in the Caribbean last year, with the US Coast Guard interdicting 50 percent more drugs in 2012 than 2011.

However, around three-quarters of potential maritime shipments identified by US authorities are allowed to sail by because there aren't enough boats and planes to intercept them. "My staff watches multi-ton loads go by," Rear Admiral Charles D. Michel of the US Coast Guard told the New York Times.

Costing as little as $500,000 to make but capable of carrying millions of dollars worth of cocaine -- the small semi-submersibles can carry two to four tons, the full submarines as much as eight -- the vessels are a hugely profitable way to smuggle drugs. However, the crew reaps a tiny fraction of the rewards. Reports of their pay vary wildly, with various articles stating crew members receive between $10,000 and $30,000 depending on their function. However given the cartels can easily find or threaten people to do it for much less, the wages of $1,500 per trip reported by High Times' interviewees seems much more plausible.

"As long as someone consumes it, there will be someone who produces cocaine, someone who transports it, and someone who sells it," as Alonso summed it up for Speigel. "And idiots like me, who are stupid enough to do this."