Leonardo da Vinci designed a paddle boat driven by mechanical paddles beneath the water.
The concept replaced dependence on wind or ordinary rowing with a powered mechanism. Cranks and gears would transmit motion from the crew to paddle assemblies, pushing the boat through the water.
Leonardo’s boat belongs to his broader interest in converting human effort into controlled mechanical movement. Like many of his engineering drawings, it records a proposed mechanism rather than a documented vessel that entered regular service.
The craft should not be called a submarine. Its propulsion system was unusual, but the boat was intended to travel on the surface. Leonardo also studied other naval devices, including diving equipment and ship-related machinery.