What underwater breathing apparatus did Leonardo da Vinci design for divers?

Leonardo da Vinci designed a diving suit intended to let a diver breathe underwater.

His concept included a watertight suit, a mask, and breathing tubes connected to air above the surface. The design was associated with underwater military operations, including the possibility of approaching enemy vessels unseen. Leonardo’s drawings show how he tried to solve the linked problems of waterproofing, buoyancy, and supplying breathable air.

The design was not the same as modern scuba equipment. It did not use a compressed-air cylinder carried by the diver, and there is no firm evidence that Leonardo’s complete apparatus was built and successfully tested in his lifetime.

Leonardo’s diving concept is often confused with a diving bell. A bell encloses air in a rigid chamber, while a diving suit is worn by the diver. His work nevertheless anticipated several principles later used in underwater equipment.