Leonardo da Vinci is commonly credited with an early submarine concept intended to travel underwater like a boat.
His notebooks contain drawings and notes about underwater vessels and military devices. The best-known account describes a submersible craft with a pointed, boat-like form and equipment for underwater operations. Leonardo was interested in secrecy beneath the water, including the possibility of approaching enemy ships without being seen.
The attribution requires caution. Leonardo’s surviving notes do not provide a complete, tested submarine design, and historians debate how much of the commonly reproduced reconstruction reflects the original sketches. Some popular descriptions also combine several separate underwater studies.
Leonardo’s concept should therefore not be called the first working submarine. Modern submarines depend on pressure-resistant hulls, ballast systems, propulsion, and life-support equipment developed much later. Leonardo’s achievement was recognizing the military and engineering possibilities of controlled underwater travel centuries before practical submarines appeared.