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Lock flight

Canal lock and lock-keeper's cottage on the Aylesbury Arm of the Grand Union Canal at Marsworth in Buckinghamshire, EnglandLock on the River Neckar at Heidelberg in GermanyThree Gorges Dam lock near Yichang on the Yangtze river, ChinaA lock is a device used for raising and lowering boats, ships and other watercraft between stretches of water of different levels on river and canal waterways.

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