THE UNDERSEA WORLD OF AQUATIC DRONES: There are at least two manufacturers promoting aquatic drones at CES. This is the FiFish P3:

This is the Navatics Mito:

Both units have built-in lighting to overcome the underwater murk, are connected to their remote control via a tether, which, assuming it doesn’t break, will likely come in handy finding the unit if its remote stops working. (Been there, done that, recovered the airborne drone from my roof.)

h/t ED