The United States Navy Sea, Air, and Land (SEAL) Teams are one of the best-known special operations organizations in the world. Still, within that small community lies a smaller group trained in niche old-school commando-style missions performed aboard a particular vessel: the SEAL Delivery Vehicle, or SDV.Powered by electricity, this small fleet of mini-submarines, not much larger than a standard shower, can strike or carry special operations officers behind enemy lines for clandestine missions. Mostly invisible to even the most advanced radars, the SDVs can reach places that standard vessels simply cannot.After hours of slow, calculated movement in pitch black darkness, the four crewmembers aboard an SDV swim the last stretch from the sea to the beach, ready to strike the enemy when it least expects it…