I watched a 30 minute documentary online about these semi-submersibles. The drug lords that are having them built have nothing but time and money. The majority of them are built in the middle of nowhere with 100% of the parts boated in from other places. The cost of the ships are around one million dollars, but a successful shipment to Mexico or the USA can net $170 million. Once the drugs are handed over to the local gangs, the sub crew scuttles the ship. Each ship has a valve that, when pulled, lets water on board.