▲Seuil de Naurouze marks the highest point (190 m, or 623 ft above sea level) of the Canal du Midi. (Photo: Wikimedia/CC BY 2.5)

▲This is the largest walled city in Europe. Its citadel—Cité de Carcassonne—was founded during the Gallo-Roman period, and is a UNESCO World Heritage Site. (Photo: Wikimedia/CC BY-SA 4.0)

▲The picturesque Saint-Joseph Bridge spans the Canal du Midi near Agde, the Mediterranean port of the canal. (Photo: Flickr/CC BY-NC 2.0)

▲The canal is served by several tour operators offering novices the chance to navigate their own barge along the entire watercourse or selected sections of the waterway. (Photo: Flickr/CC BY 2.0)

▲The Capitole de Toulouse dates back to 1750. Besides the city hall, the building houses a theater and the national orchestra. (Photo: Wikimedia/CC BY-SA 3.0)

▲The city's Musée des Augustins is a fine arts museum noted for its collection of paintings and sculpture. Originally a convent, the building's 14th-century cloisters display a number of gargoyles salvaged from demolished churches.

▲Not a hotel but in fact a 16th-century Renaissance palace, the ornate Hôtel d'Assézat houses the Bemberg Foundation, a major city art gallery. (Photo: Wikimedia/CC BY-SA 4.0)

▲Historic Béziers is one of the oldest cities in France. Must-sees include the cathedral, seen here at dusk overlooking the old town and its bridge.

▲Solid-looking and brooding, the 12th-century Agde Cathedral is built entirely out of black basalt and was designed to serve as a fortress as much as a church.

▲The Canal du Midi is a 240-km- (150-mi-) long canal in southern France. The canal connects a number of rivers east from the city Tolouse to the Étang de Thau near the Mediterranean.

▲Carcassone sits on the Aude River, which is bordered by the Canal du Midi. It's therefore an ideal place to drop anchor in and explore.

▲Traveling west-east from Toulouse to Sète, the locks numbered 1–18 are ascending and 19–86 are descending.

▲Running westwards, the canal also joins the Garonne River to form the Canal des Deux Mers, joining Toulouse with Bordeaux—and effectively the Mediterranean to the Atlantic.

▲The chapel dome of Hôpital de La Grave is reflected in the Garonne River. The Garonne joins the Canal du Midi east of the city center.

▲A cultural highlight is the remarkable Basilica of Saint-Sernin. Constructed between about 1080 and 1120, the Romanesque landmark is a UNESCO World Heritage Site.

▲From Agde, travelers have the option of navigating the La Nouvelle branch of the Canal du Midi to Sète, another Mediterranean port and a popular seaside resort.

▲The Pont Neuf arch bridge dates back to the late 16th and early 17th centuries.

▲There are over 80 working locks on the Canal du Midi from Toulouse to the Mediterranean.

▲The magnificent 13th-century Church of the Jacobins is celebrated for its vaulted roof.

▲An aerial view of scenic Castelnaudary and the canal.

▲The Canal du Midi was officially inaugurated in 1681. Once used to transport goods and people, the waterway is now mainly used by boaters and other tourists. For this voyage, we are traveling east from Toulouse and stopping at various points along the way to take in the views.

▲The 17th-century Saint-Marcel bridge in Le Somail. The town once served as the resting place for passengers on the mail barge operating between Toulouse and Agde.

▲From Seuil de Naurouze, we head eastwards towards Castelnaudary through a tranquil and pastoral countryside.

▲The waterway, a UNESCO World Heritage Site, rises in this French city, the capital of the region of Occitanie.

▲The well-known Moulin de Cugarel near Castelnaudary is a favorite visitor attraction.

▲Port Saint-Sauveur on the Canal du Midi is one of two river ports located on the waterway at Toulouse.

▲But on this journey, your voyage effectively ends at Étang de Thau, the largest of a string of lagoons located near Sète. Tie your boat up and watch the sun set.

▲The Canal du Midi cuts through this sleepy town located near Carcassonne, which is certainly worth a diversion.

▲Here, the Canal du Midi spans the Orb River as an aqueduct (pictured) called the Pont-canal de l'Orb, claimed to be the first of its kind. From here, your voyage continues to Agde.

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A remarkable work of engineering, the Canal du Midi twists and turns through some of the most beautiful countrysides in southern France. Rising in the historic city of Toulouse, this is the country's most famous canal. Every year, hire boats ply its emerald green waters, with some making the voyage all the way to the Mediterranean coast.

Browse this gallery and jump aboard for a leisurely excursion on this UNESCO-protected waterway.