Midi Canal is a historic canal in the Languedoc region of France, a major link in the inland waterway system from the Bay of Biscay of the Atlantic Ocean to the Mediterranean Sea. It was built in the 17th century at a time when France was the centre of civil engineering excellence. The Midi Canal connects Toulouse, using water from an artificial reservoir built in the Montagne Noire (Black Mountain), with the Mediterranean at Sète via the Étang de Thau (Thau Lagoon). On its 240km journey, the canal first rises 63m via 26 locks, on its 51.5km stretch from Toulouse to its 5km long summit, then descends 189 metres in 183.5 km by 74 locks to Étang de Thau.

Following World War II, the canal became important for leisure boating, for which reason it is now the most heavily used canal in France. It was Europe’s first long-distance canal and was designated a UNESCO World Heritage site in 1996.

After Leonardo da Vinci designed the first mitre gates in Milan (1497), he was brought to France in 1516 by Francis I, king of France and Milan. Leonardo looked at proposals for canals from the Garonne River to the Aude River and from the Loire River to the Saône River.

The idea of a canal to link the Atlantic and Mediterranean was not abandoned, however. Pierre-Paul, Baron Riquet de Bonrepos, together with his engineer, François Andreossy, finally overcame the main design problem of providing a sufficient water supply system for the summit with plans for building a dam. Louis XIV granted permission for the construction of the canal in 1666. Work was soon under way on the water supply system. At the time, it was the greatest civil engineering work in Europe, holding back waters from the Montagne Noire, including the Laudot River, which could feed either the canal or the reservoir via two channels with a total length of 66 km.