The Agde Round Lock (french: L'Écluse Ronde d'Agde) is a

canal lock A 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. The distinguishing feature of a lock is a fixed chamber in which the water lev ...

on the

Canal du Midi The Canal du Midi (; ) is a long canal in Southern France (french: le Midi). Originally named the ''Canal royal en Languedoc'' (Royal Canal in Languedoc) and renamed by French revolutionaries to ''Canal du Midi'' in 1789, the canal is considere ...

that connects to the

Hérault River Hérault (; oc, Erau, ) is a department of the region of Occitania, Southern France. Named after the Hérault River, its prefecture is Montpellier. It had a population of 1,175,623 in 2019.Agde Agde (; ) is a commune in the Hérault department in Southern France. It is the Mediterranean port of the Canal du Midi. Location Agde is located on the Hérault river, from the Mediterranean Sea, and from Paris. The Canal du Midi con ...

France. It is almost unique because it is round, which allows a boat to turn around, and the fact that it has three sets of lock gates, each with a different water level. It was built in 1676 of volcanic stone and was originally 29.20 m in diameter, 5.20 m deep. The lock is no longer ''round''. It was expanded during a program begun in 1978 to expand locks to the

Freycinet gauge The Freycinet gauge (french: gabarit Freycinet) is a standard governing the dimensions of the locks of some canals, put in place as a result of a law passed during the tenure of Charles de Freycinet as minister of public works of France, dating fr ...

to allow for barges up to 38.50 metres long. Originally, buildings in the area of the lock included an administration building, stables, shops, and a chapel. The exits are to

Béziers Béziers (; oc, Besièrs) is a Subprefectures in France, subprefecture of the Hérault Departments of France, department in the Occitania (administrative region), Occitanie Regions of France, region of Southern France. Every August Béziers hos ...

via the western section of the Canal du Midi, to

Étang de Thau The Étang de Thau (; oc, Estanh de Taur) or Bassin de Thau is the largest of a string of lagoons (''étangs'') that stretch along the French coast from the Rhône river to the foothills of the Pyrenees and the border to Spain in the Languedoc- ...

via the upper Hérault river and the eastern section of the Canal du Midi, and south to the

Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the e ...

via the lower Hérault river. A second French round lock can be found in the form of the now-disused Écluse des Lorraines, connecting the

Canal latéral à la Loire The Canal latéral à la Loire (, "canal parallel to the Loire") was constructed between 1827 and 1838 to connect the Canal de Briare at Briare and the Canal du Centre at Digoin, a distance of . It replaced the use of the river Loire, which wa ...

with the River Allier. Image:CdM - Ecluse Ronde d'Agde.jpg, Above, Béziers is shown to the right, Mediterranean on the top, and Etang de Thau to the left. Image:Agde Round Lock post card.jpg,

References

{{Reflist Locks on the Canal du Midi