Leonardo da Vinci sketched a diving suit as an underwater breathing apparatus for divers in Venice.
His design appears in the Codex Atlanticus and is associated with a plan to let divers approach enemy ships during a possible Venetian naval defense. The suit included a mask, breathing tubes, and a system intended to connect the diver with air at the surface.
The design was conceptual rather than a demonstrated modern scuba system. Leonardo worried that divers might use such equipment for sabotage, so he reportedly kept some details obscure. The idea is often confused with a submarine, but a diving suit is worn by a person, whereas a submarine carries people inside a vessel.
Leonardo’s diving concept belongs to his wider study of water, pressure, breathing, and military engineering. It shows how his notebooks combined practical observation with speculative designs, even when the technology needed to build them reliably did not yet exist.