From this lock, head south ward along D13 to Agde. You do not have to cycle on the road, but can cycle along the little canal next to the road.
The original lock was build in black lava rock, just like most older structures in Agde. Paul Riquet always used building materials from the surrounding area whenever possible. During the late 1970's the lock was made bigger to accommodate larger boats. Thus today the lock is not exactly round anymore. Originally the lock was 29,20 meters in diameter and 5,20 meters deep. With the "upgrade" in the 1970's, boats up to 38,50 meters can now enter this lock.
The lock is round because the canal traffic needed the options of both getting to Agde and to Sete. The Herault River, just a few meters from here, has a dam running across it to supply water to a water mill. So two canals had to be dug, one to reach the part above this dam and the other to reach the part below this dam. The dam also needed to maintain sufficient water levels during dry spells.
If you continue straight here with a boat, you will quickly join the Herault River. After sailing upstream for a few hundred meters on this river you will turn right and re-join the Canal Du Midi towards the Bassin de Thau.
If you enter the lock with your boat and turn south instead, you will also join the Herault River and from there the port of Agde. You can also continue on to the sea from here.
There are three water levels at this lock. The highest water is if you continue straight towards Sete. The medium level is the water between here and Beziers. And the lowest level is between here and the port of Agde. But overall these height differences are very small, just 44 cm maximum.
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