Leonardo da Vinci designed canal locks to help boats pass between waterways at different elevations.
Leonardo worked on hydraulic engineering projects in northern Italy, including canal systems around Milan. His notebooks show detailed interest in gates, water levels, channels, and methods for controlling the flow of water. A lock allows a vessel to enter a chamber, where gates close and the water level is raised or lowered before the boat continues.
Leonardo is especially associated with improvements to the mitre lock, whose angled gates press together under water pressure. Such designs made navigation more practical in regions where canals could not remain at one level.
Leonardo did not invent the basic principle of the canal lock from nothing; earlier forms existed. His importance lies in studying and refining hydraulic mechanisms. A canal lock is different from a dam, which primarily controls water storage or flow rather than lifting boats through a chamber.