Leonardo da Vinci designed a canal lock to regulate the water level between sections of a canal.
His work on waterways in northern Italy included improvements to canal gates and lock systems. A lock allows a boat to move between different water levels by enclosing it in a chamber, closing gates, and raising or lowering the water before opening the opposite gate.
Leonardo is particularly associated with the mitre gate, whose two leaves meet at an angle pointing toward the higher water. Water pressure helps press the gates together, improving the seal. Similar gate principles became important in the Naviglio di San Marco system in Milan.
Leonardo did not invent every form of canal lock from scratch, and earlier water-control structures existed in Europe. His contribution was the refinement and detailed study of practical canal engineering. A canal lock is therefore different from a sluice gate, which controls flow but does not normally lift or lower boats through a chamber.