But what is a narco-submarineA narco-submarine (also called a drug sub, semi-submersible, or low-profile vessel) is a covert craft built or adapted by drug traffickers to move large quantities of illegal drugs—usually cocaine—while avoiding detection by radar, aircraft, and coastal patrols.They range from crude, partially submerged boats to more sophisticated, fully submersible craft.Most smuggling vessels are semi-submersibles:they ride very low in the water so that only a small section of the hull or a narrow cockpit is visible.The most common type is the semi-submersible, or low-profile craft:The hull sits just below or barely above the waterline; only a small conning area or snorkel protrudes.Visually they’re hard to spot, and their radar signature is very small.From a naked eye at sea, these vessels are almost impossible to see.What’s inside a narco-submarine?Step inside, and you’ll find cramped, functional spaces designed to keep a small crew alive and the cargo hidden.At the front is a tiny cockpit where the pilot navigates. It’s not comfortable—just enough room for steering instruments and someone to sit for long stretches.Nearby are backup generators used to restart the engine if it stalls.