Canal Lock Keeper
Work a canal lock with gates and paddles to lift and lower a queue of boats. The water follows a real rule: it rushes in at first and creeps at the end, and a gate will not open against a difference in level. Carry boats both ways to save water, and do not keep them waiting. Six levels from a quiet canal to a busy flight.
- Strategy
- Free, plays in your browser
- Mouse, touch or keyboard
- Added 10 November 2026
- #canal
- #lock
- #boats
- #water
- #gates
- #timing
Canal Lock Keeper
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Loading Canal Lock Keeper 0%Watch a 20-second trailer
A real run of the game, recorded with captions and no sound.
How to play
- Boats queue below the lock (orange, going up) and above it (purple, going down). Use the four buttons: the lower gate, the upper gate, the Empty paddle and the Fill paddle. Press 1 to 4 on the keyboard for the same buttons in order.
- A gate only opens when the water inside is level with the pool outside, and a paddle only runs while both gates are shut. Open a paddle to fill or empty the chamber, close it when the level is reached, then open the gate and let boats in and out. Two boats fit in the chamber.
- Get at least four in five boats through before they give up waiting. Every fill takes a lockful of water from the upper pool, so the best keepers lift a boat up and lower another one down in the same cycle. Use fast-forward to speed up the waiting.
Controls: mouse, touch or keyboard. Made by CalcoTools.
Tips and strategy
- Do not run the lock for a single boat if another is about to arrive on the far side. A cycle that carries boats both ways uses half the water.
- The chamber fills fast at first and slowly at the end, so close the paddle as soon as the level is within a few centimetres of the pool.
- If a boat is crossing a gate you cannot close it, so open gates only when you are ready to hold them for the boats.
FAQ
- Why does the lock fill quickly and then slow down?
- Because the speed of water through a paddle depends on the height difference (the square root of it, in Torricelli's law). When the chamber is far below the upper pool the water rushes in, and as the levels come together the push fades away.
- Why can't I open a gate straight away?
- A full lock has tonnes of water pressing on the gate. Until the water on both sides is at the same level the force is far too large to move it, which is why real locks need their paddles worked first.
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