In the most important drug and submarine combination since the Beatles and a prime example of non-state actor super-empowerment, the Ecuadorean police recently found a 100 foot drug smuggling submarine in a jungle shipyard. Unlike the numerous semi-submersibles we've been catching which skim the surface, this vessel does not need to keep an air intake and exhaust pipe above water and thus "could evade radar and heat-seeking technology of drug-interdiction aircraft."
Nobody is surprised. We've been getting better at catching semi-subs so it was only a matter of time before smugglers took it to the next level. This is indicative of the cat-and-mouse game between detection or enforcement and crime. We see it all the time in technical intelligence, and the forces of order tend to be on the loosing end. In part this is just the nature of TECHINT- you generally need to be a few steps ahead of a system to crack it and listen in- but illicit non-state actors also tend to have information access superiority with regards to detection. In this case, drug cartels know much more about our drug-interdiction technology, which is not classified or particularly dynamic, than we do their capabilities or shifting methods. They know where our bases, borders, and patrols are, but we don't necessarily know what route they will take.
Consider how this sub was found. It wasn't caught at sea, and in all likelihood it wouldn't be. Instead, it was found on a tip while in construction, likely due to the huge supply chain needed to build such a sophisticated craft. To regularly find these submarines with TECHINT, we would need to upgrade our fleet and increase our patrols, a huge effort, and still it would be an uphill battle. We may already be letting such submarines slip by. Last year, Colombia caught 22 semi-submersibles along its coast, but this year it only found one. I don't think the traffickers just gave up.