The US Navy SEALs, America's secretive frogman-commando elite, are to get a new and enlarged pocket submarine which will allow them to travel most of the way to an objective inside in the dry and then exit through an airlock before swimming on for their final approach. Ordinary "wet" SDV mini-sub in action. The SEALs and comparable elite forces such as the British SBS have long used "wet" Swimmer Delivery Vehicles (SDVs) to approach an objective below the waves, allowing them to move faster and further than an unaided frogman can. With a normal SDV, the frog-trooper isn't inside a...