Rechargeable lithium-ion battery technology makes this radical underwater vehicle possible. The 18v, 240-watt system fully recharges in four hours and can be ready to go in just two. Depth rated to 130 feet, the Bladefish 5000 offers three speed settings for run times as long as 120 minutes and speeds up to 3.75 mph. And at just 10.2 pounds and 15 inches in diameter, it's easy to handle topside and can be checked in airline baggage.