The Seine (pronounced sayn or sen in French) is a river that is 777 kilometers long (about 483 miles) in northern France. The area that drains water into the Seine is called the Paris Basin, which is a low area in the earth's surface covering much of northern France. The river begins at a place called Source-Seine, 30 kilometers (19 miles) northwest of Dijon in northeastern France on the Langres plateau. It flows through Paris and into the English Channel near Le Havre (with Honfleur on the left side). The Seine can be traveled by large ships as far as Rouen, which is 120 kilometers (75 miles) from the sea. More than 60 percent of the river, up to Burgundy, can be used by large barges and most tour boats. Nearly the entire length of the river is suitable for recreational boating. Tour boats provide sightseeing trips along the riverbanks in Paris.

There are 37 bridges in Paris that cross the Seine (the most well-known are the Pont Alexandre III and the Pont Neuf). Many more bridges are located outside the city.

River sources

The Seine River begins in the town of Source-Seine, located about 30 kilometers (19 miles) northwest of Dijon. Since 1864, the city of Paris has owned the source of the river. The water flows from several small ditches or low areas near the source. An artificial cave was built to mark and hold the main source. Inside the cave, there is a statue of a nymph, a dog, and a dragon. At the same location, the remains of a temple from the Gallo-Roman period are buried underground. Small statues of the goddess Sequana, known as the "Seine goddess," and other offerings found there are now displayed in the Dijon archaeological museum.

Course

The Seine River can be divided into five sections:

• the Petite Seine, or "Small Seine," from where the river begins to Montereau-Fault-Yonne
• the Haute Seine, or "Upper Seine," from Montereau-Fault-Yonne to Paris
• the Traversée de Paris, or "Paris waterway," which runs through Paris
• the Basse Seine, or "Lower Seine," from Paris to Rouen
• the Seine maritime, or "Maritime Seine," from Rouen to the English Channel.

After Rouen, the river flows through the Parc Naturel Régional des Boucles de la Seine Normande, a French regional nature park.

Navigation

The Seine River is dredged, which allows large ships to dock at Rouen, 120 kilometers (75 miles) from the sea. Smaller commercial boats, such as barges and push-tows, can travel on the river starting at Marcilly-sur-Seine, 516 kilometers (321 miles) from its mouth.

In Paris, there are 37 bridges across the Seine. At a point 446 kilometers (277 miles) from the river’s mouth, the Seine is only 24 meters (79 feet) above sea level. This shallow depth makes the river flow slowly, which helps make it easier to navigate.

The Seine Maritime, a section of the river between Le Havre and Rouen, is 123 kilometers (76 miles) long and is the only part of the Seine where large ocean ships can travel. This section includes a tidal area followed by a canalized section called the Basse Seine, which has four large locks leading to the mouth of the Oise River at Conflans-Sainte-Honorine, 170 kilometers (110 miles) away. Smaller locks at Bougival and Suresnes lift ships to the level of the Seine in Paris, where the river connects to the Canal Saint-Martin. The distance from the mouth of the Oise River to this point is 72 kilometers (45 miles).

The Haute Seine, the section of the river from Paris to Montereau-Fault-Yonne, is 98 kilometers (61 miles) long and includes eight locks. At Charenton-le-Pont, the river Marne flows into the Seine. Upstream from Paris, seven locks allow navigation to Saint Mammès, where the river Loing joins the Seine. An eighth lock connects to the river Yonne at Montereau-Fault-Yonne. From the mouth of the Yonne, larger ships can travel upstream to Nogent-sur-Seine, 48 kilometers (30 miles) away, through seven locks. Beyond Nogent-sur-Seine, only small boats can travel to Marcilly-sur-Seine, 19 kilometers (12 miles) away, through four locks. At Marcilly-sur-Seine, a 19th-century canal called the Canal de la Haute-Seine once allowed ships to continue to Troyes. This canal is no longer in use since 1957.

The average depth of the Seine in Paris today is about 9.5 meters (31 feet). Before locks were built in the 1800s, the river was much shallower in the city, with only a narrow channel of flowing water surrounded by sandy banks, as shown in many historical drawings. Today, the river’s depth is carefully managed, and the entire width of the river between the city’s banks is usually filled with water. The river’s average flow is low, only a few cubic meters per second, but higher flows can occur during heavy rainfall.

Dredging work in the 1960s reduced the occurrence of tidal bores on the lower Seine, known in French as "le mascaret."

Dams and flood control

Since 1950, four large storage reservoirs have been built on the Seine River and its tributaries, the Yonne, Marne, and Aube. These reservoirs, named Lac d’Orient, Lac des Settons, Lake Der-Chantecoq, and Auzon-Temple and Amance, help keep the river level steady in Paris. However, they cannot stop the river from rising greatly during times of very heavy rain.

A major flood in January 1910 caused widespread flooding in Paris. The Seine River reached dangerous levels again in 1924, 1955, 1982, 1999–2000, June 2016, and January 2018. In 2003, after a flood warning, about 100,000 pieces of art were moved from Paris to safer places. This was the largest art relocation since World War II. Many of the artworks in Paris are stored in underground rooms that could be flooded.

A 2002 French government report said that the worst possible Seine flood could cost 10 billion euros. It would also stop telephone service for a million people in Paris, leave 200,000 without electricity, and leave 100,000 without gas.

In January 2018, the Seine River flooded again. On January 29, the river reached a flood level of 5.84 meters (19 feet 2 inches). An official warning was given on January 24 about heavy rain likely causing flooding. By January 27, the river was rising quickly. Deputy Mayor Colombe Brossel said the heavy rain was caused by climate change. She added, "We must understand that climate change is not just a word—it is a reality."

Watershed

The basin area, which includes part of Belgium, covers 78,910 square kilometers (30,470 square miles). Two percent of this area is forest, and 78 percent is used for farming. In addition to Paris, three other cities with populations over 100,000 are located in the Seine watershed: Le Havre, which is at the river’s mouth; Rouen, which is in the Seine valley; and Reims, which is at the northern edge of the area. Reims has an annual urban growth rate of 0.2 percent. The population density in the region is 201 people per square kilometer.

Tributaries of the Seine are, from source to mouth:

Water quality

The Seine-Normandy watershed, which includes Paris and its surrounding areas, faces the greatest human impact of any river system in France. This is because the region has many industries, farms, and people living close together. Compared to other large rivers in Europe, the Seine has a harder time mixing and spreading out pollution from cities and farms. For over 100 years, the river has had low oxygen levels, high amounts of ammonia, nitrites, and bacteria from waste. These problems started in the 1960s when the use of nitrogen-based fertilizers increased, leading to more pollution from farmland. Heavy industries near Paris and along the Oise River released untreated waste into the river as early as the 1800s, but these issues were not addressed until the late 1980s. France passed major laws to improve water quality in 1898, 1964, 1996, and 2006.

At the start of the 20th century, most household waste was used as fertilizer for nearby farmland. However, as the population grew, farms could no longer handle the amount of waste. To manage this, wastewater treatment plants were built beginning in 1940. By 1970, about 60% of city waste still flowed into the river without treatment. This caused oxygen levels to drop so much that only three types of fish remained. In the early 2000s, new rules from the Water Framework Directive helped reduce pollution from organic matter, phosphorus, and ammonium, which lessened harmful algae growth. More treatment plants and better methods improved the environment. By 2009, Atlantic salmon returned to the Seine. By the early 2020s, the number of fish species near Paris had grown to 32.

Paris’s sewage system sometimes fails during heavy rain, causing untreated waste to flow into the Seine. This is because the city uses a single system from the 1800s that mixes rainwater and sewage. This overflow causes bacteria larger than one micrometer to reduce oxygen levels. These bacteria are more active than the natural bacteria already in the river. Heavy metals are also common in the Seine, and the water’s pH near Pont Neuf is 8.46. Despite these issues, water quality has improved over time, even though the river was once called an “open sewer.”

In 1988, then-mayor Jacques Chirac, who later became president, called for ending a swimming ban that had been in place since 1923. In 2018, a €1.4 billion cleanup plan, called the “Swimming Plan,” was launched to prepare for the 2024 Summer Olympics. The plan included building a rainwater storage basin to prevent overflow and creating public swimming areas by 2025. While E. coli levels have sometimes been too high for safe swimming, the number of fish species has increased from two to over 30. Mayor Anne Hidalgo and President Emmanuel Macron promised to swim in the river, and Hidalgo did so in July 2024.

During the 2024 Summer Olympics, the triathlon was postponed because of poor water quality caused by a rainstorm during the opening ceremony. However, the event was held the next day after tests showed the water was safe. In July 2025, the Seine was reopened for swimming after a ban that lasted nearly 100 years.

History

The name Seine comes from the Gaulish word Sēquana, which was the name of a Celtic Gallo-Roman goddess of the river. Evidence of offerings to her was found at the river’s source. Some people incorrectly connect the name to the Latin word sequor, meaning "to follow." However, the Celtic word likely comes from the same root as the English word "sea," which is seik in Proto-Indo-European, meaning "to flow" or "to pour forth."

On March 28 or 29, 845, a Viking army led by a chieftain named Reginherus, possibly the same as Ragnar Lothbrok, traveled up the River Seine using siege towers and attacked Paris.

On November 25, 885, another Viking group led by Rollo moved up the River Seine to attack Paris once more.

In March 1314, King Philip IV of France ordered Jacques de Molay, the last Grand Master of the Knights Templar, to be burned on a scaffold on an island in the River Seine near Notre Dame de Paris.

After Joan of Arc was burned in 1431, her ashes were thrown into the Seine from the medieval Mathilde Bridge in Rouen. Some people claim this did not happen, but these claims are not supported by evidence.

On August 9, 1803, Robert Fulton, an American painter and engineer, tested his first successful steamboat in the Seine near the Tuileries Garden. The steamboat was 66 feet long and 8 feet wide. It reached speeds of three to four miles per hour against the river’s current.

Reaching the Seine was a key goal of Operation Overlord during World War II in 1944. The Allies planned to reach the Seine 90 days after D-Day. This goal was achieved. However, an expected crossing of the river did not happen because German forces in France collapsed by early September 1944. The First Canadian Army faced resistance west of the Seine, and fighting occurred in the Forêt de la Londe as Allied troops tried to block German forces from escaping across the river during the Battle of Normandy.

Some Algerian victims of the 1961 Paris massacre drowned in the Seine after being thrown into the river by French police from the Pont Saint-Michel and other places in Paris.

At the Olympics

At the 1900 Summer Olympics, the Seine River was the location for rowing, swimming, and water polo events. Twenty-four years later, in 1924, the river again hosted rowing events at Bassin d'Argenteuil, which is along the Seine north of Paris.

More than 100 years later, during the 2024 Summer Olympics, the Seine River was used for a boat parade during the opening ceremony. Each country’s team had a boat in the parade.

The river also served as the site for men’s and women’s marathon swimming events and the swimming part of the triathlon. Swimming in the Seine had been banned since 1923 because of unsafe water conditions. To improve the water quality, the French government spent €1.4 billion to reduce bacteria levels in the river. During the Olympics, water tests were done daily to check if the river was safe for swimming. These tests caused the triathlon to be delayed by one day before it took place on July 31. Some triathletes who swam in the river later became sick, but it was unclear if the river water caused their illness.

World Heritage Sites

In 1991 and again in 2024, UNESCO added the banks of the Seine in Paris, known as the Rive Gauche and Rive Droite, to its list of World Heritage Sites in Europe.

In art

During the 19th and 20th centuries, the Seine inspired many artists, including:

A song called "La Seine" was written in 1948 by Flavien Monod and Guy Lafarge.

Josephine Baker recorded a song named "La Seine."

Another song titled "La Seine," performed by Vanessa Paradis with Matthieu Chedid, was part of the original soundtrack for the 2011 film A Monster in Paris.

ABBA's 1980 song "Our Last Summer," written by Benny Andersson and Björn Ulvaeus, mentions the Seine.

• Georges Seurat's painting A Sunday Afternoon on the Island of La Grande Jatte (1884–1886) shows a scene on an island in the Seine.
• Carl Fredrik Hill painted French River Landscape, Bois-le-Roi (1877).
• Alfred Sisley's The Terrace at Saint-Germain, Spring (1875), displayed at the Walters Art Museum, shows a wide view of the Seine river valley.
• Washhouses on Seine (1937) by Andrus Johani.