Leonardo da Vinci designed a diving suit intended to let a diver breathe underwater through air supplied from the surface.
His notes describe a waterproof suit with a mask, breathing tubes, and a system of flexible pipes connected to a floating device. The design was associated with underwater military operations, including the possibility of damaging enemy ships beneath the waterline. A diver would need protection from the water as well as a way to receive air.
The concept was not a modern self-contained scuba suit. It did not use compressed air carried in cylinders, and the available materials and sealing methods would have made reliable operation difficult. Leonardo's drawings also leave practical questions about pressure, buoyancy, and breathing resistance.
The design is often linked with Leonardo's investigations of hydraulics and military engineering. It shows a correct basic insight: an underwater worker needs a continuous air path, but it should not be confused with later diving equipment.