Not all of us can afford the infrastructure costs required to support a small army of trained, captive dolphins/dachshunds for the few times a year we have the chance to go diving. Luckily, some PhD candidates invented the AQUA2.
Tethered to a remote by fibre optic or Ethernet wire, AQUA2 can explore the depths (up to 37m) with you, aiding in navigation while recording the experience.
Despite its boxy design, the AQUA2's six spinning flippers make it surprisingly agile in and out of the water. Not only does the robot make pretty good time by land or sea (watch the clip, the first-person view of the robot scuttling across the beach cracked me up for some reason); it can actually pull off very practical stunts like hovering underwater, which I assume would allow the AQUA2 to hold a flashlight steady while you looted pirate gold or searched for the real SpongeBob or whatever it is that people do underwater these days.