Inspired by the success of the military’s aircraft drones, the US Navy is aggressively pursuing its own squadron of self-driven, undersea vehicles. At the primary testing ground, the Naval Undersea Warfare Center in Newport, engineers experiment with the gadgets in the sailboat-dotted waters of Narragansett Bay. One of them recently navigated its way from Woods Hole to Newport, completing several preprogrammed tasks in what the military calls an unprecedented feat. The Navy hopes its drones will eventually pilot themselves across oceans. The vehicles are already used to detect mines and map the ocean floor. With tweaks over the next several years, the Navy says they will be applied more to intelligence gathering and, in the distant future, antisubmarine warfare.