So, about 6 years ago in the early dawn hours off the Florida Keys I actually encountered a u201cnarco submarineu201d and got to witness exactly how the Coast Guard deals with one.To start with, the submarines employed for smuggling purposes arenu2019t true submarines. A more accurate description would be a boat that looks like a submarine and has 95% of itself submerged underwater. The one I encountered had a small superstructure about two feet off the surface as well as a few pipes sticking up - frankly, Iu2019m just glad we didnu2019t hit it.The Coast Guard must have already been made aware of its presence, I assume through radar as it was a large enough object to track on the surface, and had launched one of their small boats ahead of the larger cutter to intercept it. The small boat arrived about 5 minutes after I had narrowly missed the submarine and began shadowing it waiting for the larger cutter to arrive.Once the cutter arrived there wasnu2019t much left for the submarine to do. As I mentioned it wasnu2019t a true submarine, just a mostly submerged craft, and thus didnu2019t have the luxury of diving in the hopes of evading them. The two individuals aboard stopped their submarine and came out of the top of the small pilot house superstructure that was on it where they were apprehended by the members of the Coast Guard in the smaller RIB.A local towing contractor came out and towed the vessel back to the Coast Guard station. I never found out how large the bust was and unfortunately never got a really good look at the submarine although it looked something like this but with a slightly larger pilot house where the man is sitting.To be frank, I believe in the instance I witnessed the Coast Guard got lucky. The subu2019s occupants had a poor plan, poor navigation and poor timing. Arriving 10 miles off Key West at dawn on a Saturday when a couple hundred recreational boats will be offshore fishing - poor planning, poor timing and poor navigation. Had they made the run into shore twenty or thirty miles East of their track and arrived at one of the less populated Keys in the middle of the night they would have probably never been caught.Alternatively, having a small boat meet them offshore and commence the final run into a private house on a canal where it is regularly seen would have been almost certainly successful.I say this not to prtactical tips for outwitting the Coast Guard but to illustrate just how difficult it is to patrol vast stretches of ocean. The picture above doesnu2019t illustrate how well something with a very low profile above the water can mask itself with the surface of the ocean and be almost invisible to the human eye unless youu2019re right on top of it. Additionally, even the best radars will fail to acquire a small target on a rough day making tracking them difficult - the day I encountered one was fairly calm. While I didnu2019t have radar on that boat I know with my current radar I would have been able to acquire it at 4+ miles fairly easily, the Coast Guard certainly has better radar setups than I do which gives you an idea of the range limitations of radar in tracking a small object like that. Any surface vessel needs to be relatively close (20 miles or so) to the submarine and hope there isnu2019t a lot of wave action that provides excess u201cnoiseu201d making it difficult to distinguish a subu2019s pilot house from the crest of a wave.The rendezvous at sea method is also very difficult to guard against since the vessel making the rendezvous can disguise itself as a private vessel going fishing or diving and simply return to its usual dock, never raising suspicion of its activities. Checking the thousands of private vessels that go offshore everyday is well beyond the scope of the Coast Guardu2019s abilities.While surface assets and aerial assets, including this cool blimp that flies at 10,000 feet over Big Pine Key and is equipped with all sorts of surveillance tools, are effective to an extent against narco submarines and other smuggling vessels, its a constant race to keep up with improving tactics on both sides. Who knows - we might see unmanned fully submersible subs one day.