Leonardo da Vinci designed a canal lock to regulate canal levels.
His canal engineering studies included lock gates and chambers that could help boats move between waterways at different heights. By closing gates around a vessel and allowing water to enter or leave in a controlled way, a lock could raise or lower the boat without draining the entire canal. Leonardo's drawings show attention to gate construction, water pressure, and the practical movement of boats.
Leonardo worked extensively on Milan's canal network, including projects connected with the Navigli. He did not invent the general concept of canal locks, which existed before his time, but he developed and refined designs for local hydraulic problems. A canal lock is different from a dam, which primarily holds back water, and from an aqueduct, which carries water across a landscape. Leonardo's contribution lies in detailed engineering studies and improvements rather than sole invention of the principle.