U-boat Worx’s Nemo is the world’s first production-built submersible vehicle. Power is a lithium-ion battery, and steering is via a thruster system, delivering speeds up to 3 knots. The two-person sub can dive to 330 feet, and it employs air scrubbers for eight hours of run time. Nemo weighs 5,510 pounds and requires less on-deck space than two personal watercraft. It comes with a single-point hoisting system and can be stored on flat surfaces sans cradle.