North Sea Boats' new X-18 Tank Boat feels like it should be a G.I. Joe toy. The 60-foot long catamaran can travel up rivers, carry a small inflatable boat on its back, and deliver either 20 Marines or Navy SEALs to shore. It also has a tank cannon in a turret on top of the main cabin, and if that isn't enough, it's possible to put an automated heavy machine gun turret on top of the tank turret.