Leonardo da Vinci described a diving suit for divers exploring underwater.
His notes from the early sixteenth century show a suit with a mask, breathing tubes, and a system intended to supply air to a person below the surface. The apparatus was associated with military plans for underwater operations, including the possibility of approaching enemy ships unseen.
Leonardo's concept included a flexible suit and a breathing arrangement connected to the surface. It was not a modern self-contained scuba system: the diver did not carry a compressed-air tank. The design also faced serious practical problems involving air delivery, water pressure, and the danger of carbon-dioxide buildup.
Some accounts say Leonardo hid the design because he feared it could be used for warfare. That claim is difficult to prove from the surviving material. What is certain is that his notebooks contain an early detailed concept for a wearable underwater breathing apparatus.