Leonardo da Vinci designed canal locks to control water levels and improve navigation on waterways.
A canal lock uses a chamber between two gates. Boats enter the chamber, the gates close, and water is added or released until the boat reaches the level of the next section of canal. Leonardo studied and refined lock mechanisms while working on water-management projects in northern Italy, especially around Milan. His notes include designs for gates, sluices, and other hydraulic equipment.
Leonardo is sometimes credited with inventing the canal lock, but earlier forms of locks existed before his work. His importance lies in improving and documenting practical designs, including mitre gates and systems for regulating water. Locks were valuable in regions where canals crossed uneven terrain because they allowed boats to change elevation without moving cargo overland. The same basic principle remains in modern navigation canals, although contemporary locks use stronger materials, powered gates, pumps, and automated controls.