Originally Posted by
cattletruck
I read about these underwater drones (battery powered) that have a range of thousands of kilometers - they mostly glide underwater, downwards when the ballast tanks are full and glide upwards when empty, they even have solar panels to take up a charge when resting on the surface. Too small and too quiet for detection as they go about gathering their intel.
And too slow and too comms limited to provide anything tactically useful beyond good environmental data