I propose building a mechanical manta ray as a Underwater Unmanned Vehicle; UUV. The manta ray will have air tanks inside of its wings and a sound device, which will also operate a sonar and an ELF communication system. The air tanks will be flexible rubber type tanks with an array of gases which when hit with a directional sound device will excite the air and gas molecules and expand the tanks, thus flapping the wings. The wings on the down stoke will have material memory making them go back to a neutral position. Material Memory Muscles:

http://research.dh.umu.se/dynamic/artiklar/shape/electricmuscle.html

The manta ray will have different settings for different depths and densities of water, so it can hide in trenches or maneuver up a river inlet to keep an eye on cargo ships delivering to harbors or inland ports. The manta ray can interact with sea life for oceanic studies, monitor algae blooms, map the ocean floor, watch for drug smugglers or be used in covert operations of rogue nation states.

Additionally I propose that this mechanical manta ray (MMR) system be made in many sizes and at least some should be able of flight after reaching the surface of the water. The manta ray would have a package of ten canisters of compressed gas and then balloon its way into a surveillance position to send data, video or become part of a net-centric strategy to assist Department of Homeland Security, Coast Guard, DEA or military.

http://www.uscg.mil/deepwater/pdf/FaircountDeepwater.pdf

Once airborne it can act as a communication relay and interact with all satellites, ships, cell towers, wireless military technologies, AWACS, Aircraft and other UAVs. The balloon system will operate in a similar fashion to the Georgia Tech Graduate Student