The Navy trains and uses sea lions to do some amazing things. They can recognize different types of devices (for example, radio markers or live sea-mines) and act accordingly. They can even catch unwanted divers by attaching a leg-cuff to their thighs!
The reason sea lions are used is because they are well suited for low-light activities underwater. They have a good sense of direction and their low-light abilities means that they can perform better than humans and even current technology!