La Maplouine LaMaplouine The ultimate Saint-Malo tour guide FR

La Maplouine › The Rance

The Rance Estuary: from Dinan to Saint-Malo

The Rance is only a river for its first eighty kilometres. Below the lock at the Châtelier it becomes a ria, a valley drowned by the sea, and the tide runs twenty kilometres up it. The gap between high and low water here once reached 13.50 metres, and everything else follows from that: some fifteen tide mills, havres — sheltered inlets — where the firewood for Saint-Malo was stacked, and, since 1966, the first tidal power station in the world. A decree of 6 May 1995 placed the estuary among France's classified sites, across sixteen communes, the basic unit of French local government: nothing in it may be altered without the consent of the minister.

A short river, a long arm of the sea

The Rance runs 104 kilometres according to its file at the Sandre, the French national water data bank, and rises in the monts du Mené. Everything turns on the lock at the Châtelier, just below Dinan. Above it the river is canalised: it forms the seaward section of the canal d'Ille-et-Rance, 85 kilometres and 48 locks down from Rennes, open to navigation since 28 October 1832. Below it, the lock and its weir stop the sea from climbing any further and hold the freshwater side at a fixed level, so the beat of the tide is confined to the last twenty kilometres.

The shape of this ria owes nothing to a torrent wearing down rock. The estuary crosses bands of stone aligned north-east to south-west, hard granite alternating with soft schist, and the Rance slipped into the fracture lines rather than cutting a valley of its own. Hence the sudden bends, the cluses — narrow breaches through a bar of rock — and the coves where the ebb lays bare wide mudflats.

Tidal range drives everything that follows. Before the barrage, the water level in the estuary ran from 2.30 metres at coefficient 20 — the French scale of tidal strength — to 13.60 metres at coefficient 120, figures restated by the Cerema in 2017. The tidal basin, from the barrage up to the lock at the Châtelier, covers about 2,200 hectares and holds some 180 million cubic metres, which the sea filled and emptied twice a day. Water that rises and falls more than ten metres behind a dam is free, predictable stored energy, and the valley has been drawing on it since the Middle Ages.

The Solidor tower at the water's edge, three towers joined under a high slate roof
The Solidor tower at the mouth of the Rance: three towers set together in a clover plan, built in the fourteenth century. Illustration

Tide mills, an industry born of the tidal range

The principle has not changed. A dam closes off a cove or the mouth of a stream; flap gates that open one way only let the flood tide in, then shut under the push of the water; as the tide falls, the miller lets the pond out through a sluice onto the paddle wheel. So the mill turns only while the sea stands lower than its pond, twice a day, at hours that slip back by about fifty minutes from one day to the next. The timetable moves, but neither drought nor flood ever stops the machine.

Brittany holds the bulk of the French total. The Brittany branch of the Inventaire général du patrimoine culturel, the national heritage survey, credits the region with more than two-thirds of the tide mills on the French coast, and close to three-quarters if Brittany is taken in its historic borders: on a regional scale, the second densest concentration in the world after the state of Maine. The count gives 29 mills in the Côtes-d'Armor, 38 in Finistère, 50 in the Morbihan, 9 in Ille-et-Vilaine and 12 in Loire-Atlantique. Only sixty are still standing, most of them turned into houses; two are classified as historic monuments, the stronger protection, under which the State must approve any work, and three are registered, a lighter one — among them the Beauchet mill, on the Rance.

On the tidal Rance, local surveys count fifteen or sixteen of them, and the practice is an old one in the Saint-Malo country: the Lupin mill, at Saint-Coulomb, goes back to the twelfth century. The Beauchet mill, at Saint-Père-Marc-en-Poulet, appears in the records in 1542 as a moulin banal, a mill where the lord's tenants were obliged to have their grain ground. It burned down, was rebuilt in 1882, was turned into a commercial flour mill at the beginning of the twentieth century and went over to an electric motor in 1957. It stopped in 1980, by then the last working tide mill on the Rance.

Timber, salt and gabares: what the Rance carried down to Saint-Malo

Saint-Malo and Saint-Servan heated their houses with wood from the valley. On the right bank, at Pleudihen, two havres — sheltered natural moorings — served as depots: the one at the Bas Champs and la Coquenais, and the one at the Chapelle Saint-Magloire. The boatmen bought logs and faggots there, cut in the surrounding country and in the forest of Coëtquen, piled them into man-made mounds six to eight metres high, ran their gabares — flat-bottomed barges made to settle on the mud — aground at the foot of the houses, and waited for the flood tide to take them down to their customers. The trade held on until 1914; timber for shipbuilding was loaded there as well.

A case from 1807 shows what that traffic was worth. A miller from the village, Claude Mehouars, applied to dam the anse de la Grande Planche and build a tide mill in it. On 25 May 1807 the engineer Mauger reported in favour, but on conditions that protected only the neighbouring mill of la Tourniole. The mayor and the inhabitants wrote to the prefect on 7 June 1808 asking that a channel be kept clear for the boats and the timber. The ground was sold to Méhouas on 16 September 1808: two uses of the same water, settled at the prefecture.

Salt kept the other bank alive. The salt marshes of la Goutte, at Saint-Suliac, were dug in 1736 for the comte Marot de la Garaye; the land register of 1848 still records ten settling pans behind a dyke, two mudflats acting as filters, and a slipway for loading the salt. Their income collapsed in the nineteenth century: Elvire de Cerny reports a fall from 160,000 to 250,000 francs in earlier days down to barely 20,000 francs around 1861. Théodore Chalmel dates the delivery of the last heap of salt to 1900.

Building and careening: the yards of le Minihic and la Landriais

The left bank built the boats the right bank loaded. Through the nineteenth century the anse de la Landriais, at le Minihic-sur-Rance, was given over entirely to boatyards turning out the small working craft of the river: gabares, chippes, carrelets, chaloupes. The local tourist office counts some forty yards in the commune at that period. The main one was founded in 1850 by the Saubost family; in 1880 François Lemarchand, a former deep-sea captain, took charge of it and fitted it with a steam engine in 1901. His successor Louis Lemarchand installed a heavy fuel oil engine there in 1926, driving a dynamo that electrified the workshop.

The centrepiece is the dry dock. Lemarchand had it built in 1908 on the foreshore, entirely of wood and shaped to the hull of a 45-metre vessel; it came into use in 1910. At that date there was no dry dock between Brest and Cherbourg that could take a terre-neuvier, one of the sailing ships of the Newfoundland cod fishery. Nothing in the method is mechanical: the ship is brought in at high water, a two-leaf gate is closed behind her and held shut by crossed oak beams, and the sea as it goes out leaves the hull dry long enough to careen and caulk it — to scrape the bottom and make it watertight again. The tidal range is enough on its own; anywhere else it would have taken pumps.

The dock was registered as a historic monument by order of 8 August 1996, the lighter protection, under which work has to be declared; its restoration began the same year and was completed in 2008. All along both banks the slipways, the quays and the perrés — sloping stone walls that hold the bank in place — tell the same economic story: boats came in wherever the bottom allowed, and the working day was set by the times of the tide.

1966: the tidal power station and the estuary it changed

The idea is an old one: as early as 1897 the civil engineer Pilla-Deflers proposed a dam and causeway between Saint-Servan and Dinard. The studies were taken up again in October 1940, the final designs settled in 1953, and a decree of 8 March 1957 declared the works to be in the public interest, granting the concession to Électricité de France, the state electricity company. Construction began in 1960 with cofferdams, temporary enclosures that allow the site to be drained. General de Gaulle opened the station on 26 November 1966; the plant was authorised to enter service in stages from 1 November 1967 to 31 December 1968.

The barrage crosses the estuary for 750 metres, between the pointe de la Briantais and the pointe de la Brebis. Twenty-four reversible bulb turbines of 10 megawatts generate on the flood as well as on the ebb: 240 megawatts installed, around 500 gigawatt hours a year. A lock 65 metres by 13 takes boats through, under the departmental road that runs over the top. This was the first industrial tidal power station in the world, and the most powerful until Sihwa, in South Korea, came into service in 2011.

The price is paid upstream. The reservoir is worked between the 4-metre and 12-metre marks, where the natural level had gone from 2.30 metres at coefficient 20 to 13.60 metres at coefficient 120: water levels now stand on average 2.50 metres higher than they used to, and the rise and fall is sharply reduced. In 1982 the mud laid down in the coves since 1966 was put at 20 to 40 centimetres, and a good deal more than that in the channel. The tide mills, for their part, had lost the head of water that turned them.

The local answer has a name: the Lyvet trap. In 1996 an experimental pit of 10,000 cubic metres was dug in the channel just below the lock at the Châtelier, to collect the silt and have it taken out afterwards. The method works: widening the pit, in 2000-2001, dredged out 92,000 cubic metres, under the contrat de baie, the bay management agreement signed on 20 April 1998. The pit had filled in again by 2004, and silting across the estuary picked up once more. An operation in 2014-2015 removed 65,000 cubic metres, drained on shore and then spread on the fields, where it corrects the acidity of the soil.

A classified estuary, and what you see coming down the bank

Protection came in three stages. The French Ministry of Culture registered the valley by two orders, in 1967 and 1974, a measure that does no more than require work to be declared to the prefect; individual headlands were then given the stronger protection, at Saint-Suliac in 1983 and at le Minihic in 1990. On 5 June 1991 the council of ministers finally picked out four large sites to be protected whole, the Rance among them. After public inquiries in 1993, the decree of 6 May 1995 classified the estuary across sixteen communes of the Côtes-d'Armor and Ille-et-Vilaine: 3,127 hectares, of which 1,126 belong to the public maritime domain — a strip of land from zero to 300 metres wide, the great mudflats, and, upstream of a line from Mordreuc to le Chêne Vert, the whole body of water. Nothing in a classified site may be altered without the consent of the minister.

Two further schemes have been added since. The special area of conservation called Estuaire de la Rance, designated by an order of 17 February 2014 under the European Natura 2000 network, covers 2,785 hectares in seventeen communes, 925 of them at sea; it protects mudflats, salt meadows and brackish seagrass beds, and it shelters the otter. The îlots Notre-Dame and Chevret make up a separate special protection area, designated in 2006 for its terns. Lastly, the decree of 19 October 2024 designated the regional nature park Vallée de la Rance-Côte d'Émeraude for fifteen years, sixty-six communes over about 90,000 hectares. Protecting an estuary means protecting a rhythm: here it is the tide, not the soil, that makes the habitats.

Coming down from Dinan, the valley reads in order. The lock at the Châtelier marks the end of the fresh water, with the port du Lyvet and its sediment trap facing it. Then come the deep-cut meanders, the cliff at Mordreuc, the havres of Pleudihen, and the pont Saint-Hubert. The estuary widens after that: Saint-Suliac, the Mont Garrot standing 73 metres above it, and to the east the bras de Châteauneuf with its salt marshes and the Beauchet mill. Lower down open the île Notre-Dame, the yards of la Landriais and the barrage.

A house above the Rance foreshore, behind its retaining wall
A house on the bank, above the foreshore the tide uncovers twice a day. Illustration

Twenty of these places in La Maplouine

The map holds more than 950 of them. Here are twenty that belong to this subject, with their commune and their category. Each one carries a full note in the map, in English and in French, geolocated and read on the spot.

La Maplouine gathers more than 950 geolocated notes across Saint-Malo, the Rance and the Clos-Poulet. It opens in Google Maps, with no account to create and no app to install, in English and in French.

Get the map Try it with 50 free places

Questions La Maplouine answers

When did the Rance barrage come into service, and how powerful is it?

General de Gaulle opened the tidal power station on 26 November 1966, after a concession decree of 8 March 1957 and construction that began in 1960; the plant was authorised to enter service in stages from 1 November 1967 to 31 December 1968. The barrage crosses the estuary for 750 metres and carries twenty-four bulb turbines of 10 megawatts, which makes 240 megawatts installed and around 500 gigawatt hours a year.

How many tide mills are there on the Rance and in Brittany?

Local surveys count fifteen or sixteen tide mills on the tidal Rance. On a regional scale, the Inventaire général du patrimoine culturel records 29 mills in the Côtes-d'Armor, 38 in Finistère, 50 in the Morbihan, 9 in Ille-et-Vilaine and 12 in Loire-Atlantique; only sixty of them are still standing. Brittany accounts for more than two-thirds of all the tide mills on the French coast.

Why is the Rance silting up?

Silt settles in the neighbouring rias too, where nothing has been built, but the barrage has made matters worse. By working the reservoir between the 4-metre and 12-metre marks, where the water used to rise naturally to 13.60 metres at the strongest tidal coefficients, it keeps levels on average 2.50 metres higher and slows the currents, which lets the mud drop out. In 1982, 20 to 40 centimetres of mud were measured in the coves, laid down since 1966.

What is the Lyvet sediment trap for?

It is a pit dug in the channel, just below the lock at the Châtelier, where silt carried in suspension settles and is then dredged out. A first trial of 10,000 cubic metres was run in 1996, then widening the pit dredged out 92,000 cubic metres in 2000-2001. The sediment is drained on shore and afterwards spread on the fields to correct the acidity of the soil.

Is the Rance estuary protected, and since when?

Yes, on several counts. The valley was first registered in 1967 and 1974, then classified as a site by the decree of 6 May 1995: the classification covers sixteen communes and 3,127 hectares, of which 1,126 belong to the public maritime domain. To that are added the Natura 2000 area designated on 17 February 2014 over 2,785 hectares, and the regional nature park created by the decree of 19 October 2024.

How far up the Rance does the tide reach?

As far as the lock at the Châtelier, at Saint-Samson-sur-Rance, some twenty kilometres up from the mouth. The lock and its weir stop the sea from climbing further and hold a fixed level above it, all the way to the port of Dinan. Beyond that begins the freshwater Rance, taken by the canal d'Ille-et-Rance towards Rennes, where the level depends on nothing but the flow and the working of the locks.

What can you see in the Rance valley in a day?

One coherent route follows the river from the top down: the lock at the Châtelier and the port du Lyvet, the cliff at Mordreuc, the timber havres of Pleudihen, Saint-Suliac and the Mont Garrot for the wide view, the bras de Châteauneuf with its salt marshes and the Beauchet mill, and finally the dry dock at la Landriais, in le Minihic, and the barrage.

Read next

The malouinièresMany malouinières, the country houses of the Saint-Malo shipowners, look down on the Rance from their terraces: the page devoted to them says who had them built, and with what money.History of Saint-MaloThe town that the timber and the salt of the Rance supplied has a chronology of its own, from the monastery at Aleth to the rebuilding after the war: the history page of Saint-Malo lays it out.Daily life in the townThe millers, bargemen and shipwrights named here lived by precise rights and customs: the page on everyday life goes into that daily round.
Sources for this page
  • https://patrimoine.bzh/gertrude-diffusion/dossier/IA35131018 — Inventaire général du patrimoine culturel de Bretagne, enquête thématique « Les moulins à marée de Bretagne » : part bretonne du corpus français (plus des deux tiers, près des trois quarts en Bretagne historique), deuxième concentration mondiale derrière le Maine, décompte par département (22 : 29, 29 : 38, 56 : 50, 35 : 9, 44 : 12), 60 moulins subsistant en élévation, deux classés et trois inscrits au titre des monuments historiques dont le Beauchet, principe technique du moulin à marée, moulin de Landounic à Saint-Pol-de-Léon daté de la fin du VIe siècle, moulin du Lupin à Saint-Coulomb au XIIe siècle.
  • https://patrimoine.bzh/gertrude-diffusion/dossier/IA35000451 — Inventaire général, moulin à marée puis minoterie de Beauchet (Saint-Père-Marc-en-Poulet) : attestation en 1542, moulin banal, reconstruction en 1882 après incendie, conversion en minoterie, moteur électrique en 1957, arrêt en 1980 comme dernier moulin en fonctionnement sur la Rance.
  • https://pop.culture.gouv.fr/notice/merimee/IA35000661 — Base Mérimée, usine marémotrice de la Rance : projet Pilla-Deflers de 1897, reprise des études en octobre 1940, études définitives en 1953, décret de concession du 8 mars 1957, batardeaux de 1960-1961, inauguration du 26 novembre 1966, mise en service progressive autorisée du 1er novembre 1967 au 31 décembre 1968, 750 mètres entre la pointe de la Briantais et la pointe de la Brebis, 24 groupes de 10 000 kW.
  • https://www.edf.fr/usine-maremotrice-rance/produire-de-lelectricite — EDF, exploitant : longueur totale du site 750 m, 24 groupes bulbes de 10 MW, débit turbiné 6 600 m3/s et débit aux vannes 9 600 m3/s, écluse de 65 m sur 13 m, retenue de 20 km et 2 200 hectares, production annuelle d'environ 500 GWh, amplitude maximale de 13,50 m.
  • https://igedd.documentation.developpement-durable.gouv.fr/documents/Affaires-0009658/010860-01_rapport_publie.pdf — CGEDD-CGE, rapport 010860-01, « Gestion sédimentaire de l'estuaire de la Rance », 2017 : marnage naturel de 2,30 m (coefficient 20) à 13,60 m (coefficient 120) rappelé d'après le Cerema, gestion de la retenue entre les cotes 4 et 12 m, niveaux d'eau en moyenne 2,50 m plus hauts qu'auparavant, réservoir de 180 millions de m3 pour 22 km2, sédimentation de 20 à 40 cm dans les anses mesurée par le LCHF en 1982 et plus forte dans le chenal à Mordreuc, historique du piège du Lyvet (fosse de 10 000 m3 en 1996, élargissement à 92 000 m3 en 2000-2001 dans le cadre du contrat de baie signé le 20 avril 1998, 65 000 m3 extraits en 2014-2015), prototype unique au monde jusqu'à Sihwa en 2011.
  • https://www.igedd.developpement-durable.gouv.fr/IMG/pdf/140709_Gestion_des_sediments_de_la_Rance_-_avis_delibere_cle1ac374.pdf — Autorité environnementale, avis délibéré du 9 juillet 2014 : piège du Lyvet de 2,7 hectares comblé dès 2004, station de transit du Petit Châtelier, valorisation agricole des sédiments (marnes, tangue) comme correcteur d'acidité et non comme fertilisant.
  • https://www.persee.fr/doc/jhydr_0000-0001_2009_act_31_1_5935 — Susperregui, Laguionie, Jigorel et Lang, « Gestion des sédiments dans le bassin maritime de la Rance », 31es Journées de l'hydraulique, 2009 : expérimentation du piège à sédiments engagée par le comité COEUR dès 1995, capacité portée à 91 000 m3 en 2001.
  • https://www.letelegramme.fr/cotes-d-armor/dinan-22100/tout-savoir-sur-ce-chantier-hors-norme-qui-a-commence-sur-la-rance-6885936.php — Le Télégramme, 9 septembre 2025 : campagne de dragage visant environ 90 000 m3 au piège du Lyvet et au port de Plouër-sur-Rance, sous maîtrise d'ouvrage de l'EPTB Rance.
  • https://www.bretagne.developpement-durable.gouv.fr/les-sites-classes-en-cotes-d-armor-a1155.html — DREAL Bretagne, liste des sites classés des Côtes-d'Armor : classement de l'estuaire de la Rance par décret du 6 mai 1995, liste nominative des seize communes concernées dans les deux départements, superficie de 3 127 hectares dont 1 126 de domaine public maritime.
  • https://pmb.bretagne-vivante.org/pmb/opac_css/doc_num.php?explnum_id=7122 — Colette Debroise-Delbreil, inspectrice régionale des sites à la DIREN Bretagne, « L'estuaire de la Rance, un site classé » : inscriptions de 1967 et 1974, classements ponctuels du 30 mai 1983 à Saint-Suliac et du 23 mars 1990 au Minihic, décision du conseil des ministres du 5 juin 1991 retenant quatre grands sites dont la Rance, enquêtes publiques de 1993, avis du Conseil d'État du 2 mai 1995, signature du décret le 6 mai 1995, périmètre (bande terrestre de 0 à 300 m, bande maritime de 50 m, grandes vasières, plan d'eau intégral en amont de la ligne Mordreuc-le Chêne Vert), 1 384 hectares de terrains nouvellement classés, bassin maritime de 2 200 hectares, géologie de la ria et tracé suivant les lignes de fracture.
  • https://www.ille-et-vilaine.gouv.fr/Actions-de-l-Etat/Environnement-et-energie/Biodiversite-chasse-peche-faune-et-flore/Aires-protegees/Natura-2000/Natura-2000-en-Ille-et-Vilaine/Estuaire-de-la-Rance-et-Ilots-Notre-Dame-et-Chevret — Préfecture d'Ille-et-Vilaine : zone spéciale de conservation FR5300061 « Estuaire de la Rance » désignée par arrêté du 17 février 2014, 2 784,91 hectares dont 925,20 hectares marins, dix-sept communes, habitats et espèces (prés salés, salicornes, herbiers saumâtres, loutre, sept espèces de chauves-souris) ; zone de protection spéciale FR5312002 « Îlots Notre-Dame et Chevret » désignée le 7 mars 2006.
  • https://www.parcs-naturels-regionaux.fr/vallee-de-la-rance-cote-demeraude — Fédération des parcs naturels régionaux : parc naturel régional Vallée de la Rance-Côte d'Émeraude classé le 19 octobre 2024, 66 communes, environ 90 000 hectares ; décret n° 2024-946 du 19 octobre 2024 (Légifrance, JORFTEXT000050375671), classement pour quinze ans.
  • https://patrimoine.bzh/gertrude-diffusion/dossier/IA22132954 — Inventaire général, écart des Bas Champs et de la Coquenais (Pleudihen-sur-Rance) : commerce du bois jusqu'en 1914, achats dans la forêt de Coëtquen, tertres artificiels de 6 à 8 mètres, gabares échouées au pied des maisons, levée de terre postérieure au barrage de 1966 et perrés antérieurs, niche à Vierge datée de 1871, chanvrils et tisserand au cadastre de 1844, cordonneries pour la pêche à Terre-Neuve.
  • https://patrimoine.bzh/gertrude-diffusion/dossier/IA22132955 — Inventaire général, écart du havre de la Chapelle Saint-Magloire (Pleudihen-sur-Rance) : moulin de la Tourniole en service dès le Moyen Âge, demande de Claude Méhouas, avis de l'ingénieur Mauger, pétition des habitants, entrepôt de bois à feu pour Saint-Malo et Saint-Servan, bois pour les constructions maritimes de l'État et du commerce, prélèvement de marnes et de goémons comme engrais.
  • https://patrimoine.bzh/gertrude-diffusion/dossier/IA35000512 — Inventaire général, chantier naval de la Landriais (Le Minihic-sur-Rance) : anse entièrement occupée par des chantiers au XIXe siècle, construction de gabares, chippes, carrelets et chaloupes, fondation en 1850 par la famille Saubost, reprise en 1880 par François Lemarchand ancien capitaine au long cours, machine à vapeur en 1901, moteur Duvant et électrification en 1926, cale sèche en bois épousant une coque de 45 mètres construite en 1908 et mise en service en 1910, seule cale sèche entre Brest et Cherbourg pour un terre-neuvier, porte à deux vantaux bloqués par des chênes croisés, inscription au titre des monuments historiques par arrêté du 8 août 1996, restauration entamée en 1996 et inaugurée en 2008.
  • https://pop.culture.gouv.fr/notice/merimee/%20PA35000001 — Base Mérimée, notice de protection PA35000001, cale sèche de la Landriais : localisation au Minihic-sur-Rance sur le domaine public maritime, construction datée de 1908, maître d'œuvre François Lemarchand.
  • https://patrimoine.bzh/gertrude-diffusion/dossier/IA35046209 — Inventaire général, marais salants de la Goutte ou des Guettes (Saint-Suliac) : creusement en 1736 pour le comte de la Garaye, dix bassins de décantation et digue au cadastre de 1848, deux vasières filtrantes, cale au sel, noms des salines (Séraphine, Clothilde, Zoé, la Goutte, Malécaire, la Girouette), effondrement des revenus rapporté par Elvire de Cerny, dernier tas de sel livré en 1900 selon Théodore Chalmel.
  • https://fdmf.fr/les-moulins-a-maree-de-la-rance-et-de-la-cote-d-emeraude-au-fil-de-l-histoire/ — Fédération des moulins de France, présentation du travail de Marie-France Porte : vingt moulins recensés sur la Rance et la Côte d'Émeraude, ancienneté du moulin du Lupin, arrêt du Beauchet en 1980.
  • https://www.ouest-france.fr/culture/patrimoine/les-moulins-a-maree-de-la-rance-un-patrimoine-fragile-et-difficile-a-entretenir-7dbbc016-d7b9-11ee-80d9-70055cb6efe2 — Ouest-France, 3 mars 2024 : seize moulins à marée sur la Rance, dont trois disparus et quatre en ruine.
  • https://fr.wikipedia.org/wiki/Canal_d%27Ille-et-Rance et http://www.fluviacarte.com/fr/voies-navigables/region-ouest-2/voie-canal-d-ille-et-rance-32 — canal d'Ille-et-Rance : 85 kilomètres, 48 écluses, chantier ouvert en 1804, ouverture officielle le 5 octobre 1832 et ouverture à la navigation le 28 octobre 1832.
  • https://fr.wikipedia.org/wiki/Rance_(fleuve) — longueur de 103,56 km d'après la fiche Sandre J0--0160, source à 258 mètres d'altitude dans les monts du Mené, ancienne commune de Collinée.
  • https://www.dinardemeraudetourisme.com/les-incontournables/balade-minihic-chantiers-navals/ — Dinard Émeraude Tourisme : une quarantaine de chantiers navals au Minihic-sur-Rance au XIXe siècle, trois aujourd'hui.
  • Audit contradictoire du 6 août 2026 : la page a été relue par un auditeur chargé d'y chercher ce qui est faux, puis les corrections introduisant un chiffre neuf ont été soumises à un second lecteur chargé de les réfuter. Les corrections réfutées n'ont pas été appliquées.