Barge arriving at the Bougival lock.

The purpose of building a second “Marly Machine”, undertaken under Charles X and later under Napoléon III, was to restore river traffic, by building a lock.

The oldest of them was built in 1838 between the Island of La Loge and Gautier Island. Following an increase in the number of small boats passing through its waters, two other locks were added in 1883. At their level, walkers can enjoy an interesting view overlooking the Seine and the boat traffic.