Der Spiegel has an interesting story regarding the Colombian drug smugglers’ homemade submarines. These have so far been considered a curiosity, but apparently they are becoming more and more common, and the technology is developing fast. The biggest vessel captured so far displaced 46 tonnes, presumably surfaced, with a payload of 10 tonnes. Apparently the current ones, described as the third generation, have a radius of action of 2,500 kilometres; an American admiral is quoted as expecting them to eventually start crossing the Atlantic from northeastern Brazil to West Africa, linking up with the emerging drugs route from there to Europe.
most of these are semi-submersibles… they are more-or-less the same as the “go fasts” normally used by smugglers, except they’ve had their decks faired over and have been weighted own with lead in the keel to make them run very low in the water – the best will float with decks awash. They have a snorkel arrangement for the diesels and a small conning tower for the operator, and only make 5-10 knots. They can carry very large drug loads, however, and are very cost effective for the smugglers.