Leonardo da Vinci designed canal locks to move boats between stretches of water at different elevations.
Leonardo worked on hydraulic engineering in northern Italy, where canals supported transportation, irrigation, and urban water management. His drawings include lock gates and canal arrangements that helped control water levels and let vessels pass through changes in elevation. The Naviglio di San Marco in Milan is commonly associated with improvements linked to Leonardo’s engineering work.
A canal lock is not a machine that carries a boat mechanically. It is a chamber with gates: a boat enters, the water level is raised or lowered, and the vessel then exits at the new level. This made navigation possible where a continuous level waterway did not exist.
Leonardo did not invent the general idea of locks, which had earlier examples in China and Europe. His contribution was the study and refinement of hydraulic systems, gates, channels, and practical navigation problems.