Leonardo da Vinci designed canal-lock mechanisms to help boats move between waterways at different levels.
Leonardo worked on hydraulic engineering in northern Italy, where canals supported transport, irrigation, and urban water management. His studies included gates and chambers that could control water flow and raise or lower a boat. A lock allows a vessel to enter an enclosed chamber, after which the water level is changed before the next gate opens.
Leonardo is strongly associated with improvements to the modern miter-gate lock, especially through work connected with the Naviglio di Martesana near Milan. Earlier forms of locks existed before him, so it is inaccurate to call him the sole inventor of the canal lock. His contribution was the study and refinement of practical hydraulic designs.
A canal lock is different from an aqueduct, which carries water over an obstacle, and from a sluice gate, which mainly regulates flow. The lock’s defining feature is its controlled chamber for changing elevation.