Video games and sci-fi movies are full of all sorts of fantastic machines and vehicles that look badass on the screen but would be completely impractical in real life. The reason you're not driving to work every day in a giant lumbering crab tank is because at some point humanity realized that wheels were way easier, and we're apparently a species that settles. Or at least, we were. Meet the Crabster:
Using 6-legged locomotion to safely traverse the seafloor at breakneck speeds of up to 1 mile per hour, the Crabster weighs in at 1,400 pounds and is controlled remotely through a 500-meter tether. The cable serves to relay information back to headquarters, and also to ensure that Cthulhu doesn't partake of a little twelve-tentacle discount.
The craft responded well to initial underwater testing, and now has its first official job on an archaeological recovery mission in the Yellow Sea, where previous craft have proven ... unworthy.