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Saint-Denis on Réunion seen from a hillside lookout: green trees and white buildings in front, a sports ground with a red running track, the city spreading along the coast and the blue Indian Ocean under a sky with white clouds

City Africa

Saint-Denis

Saint-Denis is a city by the sea on Réunion. Réunion is a mountain island in the Indian Ocean.

Saint-Denis is the main town of Réunion, a volcanic island in the Indian Ocean east of Madagascar. It lies on the island's north coast, between two rivers, with mountains around it. In 2023, 155,634 people lived in its commune, according to France's statistics office.

Saint-Denis, the main town (chef-lieu) of Réunion on the island's north coast (Larousse), had 155,634 inhabitants in its commune on 1 January 2023 and 192,727 in its agglomeration (INSEE, via City Population). Universalis describes it on a flood-prone alluvial fan between two rivers, ringed by an amphitheater of mountains.

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Photo: Clémenceau Lauret, CC BY-SA 4.0, via Wikimedia Commons

Discover Saint-Denis

Saint-Denis is a city on Réunion, an island in the warm Indian Ocean.

Mountains rise all around it.

Saint-Denis is the main town of Réunion, says the French encyclopedia Larousse. It lies on the north coast of the island, which is entirely volcanic and sits in the Indian Ocean, 560 kilometers east of Madagascar. Larousse calls it a center for offices and trade.

France's statistics office, INSEE, gives 155,634 people for Saint-Denis's commune on 1 January 2023, and 192,727 for its agglomeration, the town together with the built-up places around it.

Larousse ('Saint-Denis 97400'): chef-lieu of Réunion, on the island's north coast; 151,997 inhabitants (2018 census); an administrative and commercial center with food industries; the Léon-Dierx museum (paintings and drawings). Universalis ('SAINT-DENIS, La Réunion', Guy Fontaine): 146,489 inhabitants (2013) on 3,500 hectares; the town gathers the island's urban population, jobs and senior staff. City Population (from INSEE): commune 109,072 (1982), 121,999 (1990), 131,557 (1999) at the censuses, then 140,733 (2007), 146,985 (2015) and 155,634 (1 January 2023), which City Population labels estimates (since 2006 France computes populations from census results of different years), first among Réunion's communes; agglomeration 192,727 (2023); Réunion 889,679 (2023). Larousse ('La Réunion'): an island of the Indian Ocean at 21° south, 560 km east of Madagascar, entirely volcanic.

Island
Réunion, a volcanic island in the Indian Ocean, 560 km east of Madagascar (Larousse)
People in the commune (INSEE, 1 January 2023)
155,634
Role
main town of Réunion, on the island's north coast (Larousse)
Agglomeration (INSEE, 1 January 2023)
192,727 people
Saint-Denis on Réunion seen from a hillside lookout: green trees and white buildings in front, a sports ground with a red running track, the city spreading along the coast and the blue Indian Ocean under a sky with white clouds
Photo: Clémenceau Lauret, CC BY-SA 4.0, via Wikimedia Commons

The city from a hillside lookout

Look at the blue ocean and the white buildings!

There is a big green sports field with a red running track.

Clémenceau Lauret took this photo on 14 December 2025 from a lookout on the Montagne road. His description says it shows the Bellepierre neighborhood, sports grounds and the Indian Ocean. Green trees and white buildings are in front, a playing field with a red running track is in the middle, and the city spreads along the coast under a blue sky with white clouds.

Larousse names the Léon-Dierx museum, with paintings and drawings. On Wikidata, the Jardin de l'État, a historic garden, is about 1 kilometer south-southeast of the town's point.

Commons: File:Saint-Denis vu depuis le belvédère de la Montagne.jpg, by Clémenceau Lauret (own work, uploader = author, CC BY-SA 4.0), dated 14 December 2025 from the Exif data, uploaded 30 January 2026; his French description: a panoramic view of Saint-Denis taken from the lookout on the Montagne road, showing the Bellepierre neighborhood, sports facilities and the Indian Ocean behind; his own categories 'Saint-Denis (Réunion)', 'Panoramics in Réunion' and 'Ile de la Réunion' (another Commons user replaced them in March 2026 with 'Views of Saint-Denis (Réunion)' and 'Clouds and blue sky in Réunion'); recorded camera point 20.8793° S, 55.4455° E. Seen in the 1,280-pixel copy: trees and white buildings in front, a playing field with a red running track and a second field, the city along the coast, the ocean and a sky with clouds. Wikidata from the town point (Q47045): Musée Léon-Dierx (Q3329255) 0.58 km SSE; Jardin de l'État (Q3162482), a historic garden, 1.02 km SSE; Muséum d'histoire naturelle de la Réunion (Q3330880) 1.02 km SSE.

In the photo
Saint-Denis from the lookout on the Montagne road, 14 December 2025 (Clémenceau Lauret)
Léon-Dierx museum
a museum of paintings and drawings (Larousse)
Jardin de l'État
a historic garden about 1 km south-southeast of the town's point (Wikidata)
Saint-Denis on Réunion seen from a hillside lookout: green trees and white buildings in front, a sports ground with a red running track, the city spreading along the coast and the blue Indian Ocean under a sky with white clouds
Photo: Clémenceau Lauret, CC BY-SA 4.0, via Wikimedia Commons

A lower town and an upper town

The first homes in Saint-Denis were built long ago, in the lower town.

Now homes also cover the gentle slopes, and the city is spreading east.

Universalis says the first homes in Saint-Denis were built in the 17th century in the lower town, which is now very densely built. The center, the upper town, is laid out on a checkerboard street plan, and homes spread up the gentle slopes formed by lava flows.

The commune had 109,072 people in 1982 and 155,634 in 2023. Universalis says the city is now spreading east.

Universalis ('SAINT-DENIS, La Réunion'): the center, or upper town, follows a checkerboard plan; the lower town, where the first homes were built in the 17th century, has become densely built neighborhoods; the south and the heights of the planèze (gentle slopes formed by volcanic flows) hold well-off residences; the town is spreading east; its future is closely tied to managing the water of its rivers and of the sea. City Population (INSEE): commune 109,072 (1982), 121,999 (1990), 131,557 (1999) at the censuses; 140,733 (2007), 146,985 (2015), 155,634 (2023) as estimates.

17th century
the first homes were built in the lower town (Universalis)
The center
the upper town, laid out on a checkerboard street plan (Universalis)
1982 to 2023
the commune grew from 109,072 to 155,634 people (INSEE, via City Population)

Through the years

Between rivers, mountains and the sea

Saint-Denis sits between two rivers, with mountains all around.

Airplanes land at an airport east of the city.

Universalis says Saint-Denis is built on an alluvial fan, a fan of mud, sand and stones left by rivers. It sits between two rivers whose flow changes a lot, so the ground can flood, and an amphitheater of mountains surrounds it.

Larousse names Gillot as the airport of Saint-Denis. On Wikidata, the airport is about 7.2 kilometers east of the town's point, and the Rivière Saint-Denis flows about 0.6 kilometers to the northwest.

Universalis: 'situated in the north of the island, on a flood-prone alluvial fan between two rivers with capricious flow, surrounded by an amphitheater of mountain massifs'; the town's future depends on mastering the water of its rivers and the sea. Larousse ('Gillot'): the airport of Saint-Denis. Wikidata from the town point: Roland Garros Airport (Q17430) 7.21 km E; Rivière Saint-Denis (Q3433800) 0.61 km NW; bay of Saint-Denis (Q3416394) 0.91 km WNW; the port of Saint-Denis (Q111387342) 1.37 km N.

The site
a flood-prone alluvial fan between two rivers, ringed by mountains (Universalis)
Airport
at Gillot (Larousse), about 7.2 km east of the town's point (Wikidata)
Rivière Saint-Denis
a river about 0.6 km northwest of the town's point (Wikidata)

Warm, with a hot and rainy season

Saint-Denis is warm all year.

The rainy season is also the hot season, from November to May.

The German weather service's climate table for Saint-Denis-Gillot, by the airport east of the city, shows daytime highs from 24.5 °C in August to 29.9 °C in February. Nights range from about 17 °C to 23 °C.

About 1,632 millimeters of rain fall in a year. March is the wettest month, with 304 millimeters, and October the driest, with 38. Larousse says the rainy season is the hot season, from November to May, and it is also the season of cyclones.

Deutscher Wetterdienst, 'Klimatafel von Saint Denis-Gillot' (20° 54' S, 55° 31' E, 10 m; 7.50 km ESE of the town point; temperature period 1953-1970, rainfall 1951-1980, rain days of at least 1 mm 1968-1984, as printed in the table): mean daily maximum 24.5 °C (Aug) to 29.9 °C (Feb), year 27.2 °C; mean daily minimum 17.2 °C (Aug) to 23.0 °C (Feb), year 20.0 °C; rainfall 38 mm (Oct) to 304 mm (Mar), year 1,632 mm; 125 days a year with at least 1 mm; 7.3 hours of sunshine a day; mean sea temperature 25.0 °C. Larousse ('La Réunion'): a marked climate contrast, with about 4 m of rain a year at Saint-Benoît on the windward east side but only 700 mm at Saint-Paul on the dry west side; the rainy season (November to May) is the hot season and the season of cyclones; at sea level, mean temperatures near 25 °C on the leeward side and 23 °C on the windward side; about 5 °C lower at 1,000 m.

February, average daily high and low (DWD, Saint-Denis-Gillot)
29.9 °C and 23.0 °C
August, average daily high and low (same table)
24.5 °C and 17.2 °C
Rain in a year (same table)
1,632 mm, on about 125 days with at least 1 mm

Volcanoes, cirques and a national park

Réunion has a very tall mountain and a volcano that still erupts.

A big national park covers much of the island.

Larousse says Réunion is made of volcanoes. The older part rises to Piton des Neiges, 3,069 meters high, and is cut by three huge bowl-shaped valleys called cirques: Cilaos, Salazie and Mafate. In the southeast, the Piton de la Fournaise, 2,631 meters high, is the island's active volcano, and its lava flows sometimes reach the sea.

Réunion National Park covers 40 percent of the island. Above 1,000 meters grow bamboo and tamarind trees, and heathland reaches up to the summit.

Larousse ('La Réunion'): entirely volcanic, mostly basalt; an older part (between 2 million and 450,000 years old), built by four great successive volcanoes, and a younger part with active volcanism; the older edifice, gashed by the cirques of Cilaos, Salazie and Mafate, peaks at Piton des Neiges (3,069 m), with cliffs of more than 1,000 m above the cirque floors and long, regular planèze slopes down to the sea; the younger southeast is the Fournaise massif, with three nested calderas; Piton de la Fournaise (2,631 m) at the center of the youngest; most lava flows come from side fissures and run down the Grand-Brûlé slopes, sometimes to the sea; forest on the windward side and dry bush below 600 m on the leeward side at first, much of the eastern forest cleared below that height for sugarcane; bamboo and tamarind stands above 1,000 m, then heath (Philippia montana) up to the summit; the national park covers 40 percent of the island. Wikidata: Piton des Neiges (Q1545452), 3,070 m, 24.67 km S of the town point.

Highest peak
Piton des Neiges, 3,069 m (Larousse)
Active volcano
Piton de la Fournaise, 2,631 m, in the southeast (Larousse)
Réunion National Park
40 percent of the island (Larousse)
Saint-Denis on Réunion seen from a hillside lookout: green trees and white buildings in front, a sports ground with a red running track, the city spreading along the coast and the blue Indian Ocean under a sky with white clouds
Photo: Clémenceau Lauret, CC BY-SA 4.0, via Wikimedia Commons

Saint-Denis on the map

Find Africa on the globe. East of it is the big island of Madagascar, and farther east is little Réunion!

Saint-Denis lies at about 20.88° south and 55.45° east, on the north coast of Réunion, 560 kilometers east of Madagascar.

On Wikidata, the Léon-Dierx museum is about 0.6 kilometers from the town's point, the Jardin de l'État about 1 kilometer south-southeast, the airport about 7.2 kilometers east and Piton des Neiges about 25 kilometers south.

Saint-Denis lies at about 20.88° S, 55.45° E (Wikidata point of Saint-Denis, Q47045; the sheet point is within 0.01 km of it). Larousse: Réunion lies at 21° S, 560 km east of Madagascar. Wikidata from the town point: Musée Léon-Dierx 0.58 km SSE; Rivière Saint-Denis 0.61 km NW; Jardin de l'État 1.02 km SSE; Roland Garros Airport 7.21 km E; Piton des Neiges 24.67 km S.

Latitude
about 20.88° south
Longitude
about 55.45° east
Nearest big island
Madagascar, 560 km to the west (Larousse)

Amazing facts

  • On Réunion, one side of the island gets much more rain than the other!

    Larousse says about 4 meters of rain fall in a year at Saint-Benoît on Réunion's windward east side, but only about 700 millimeters at Saint-Paul on the dry west side.

    Larousse ('La Réunion'): about 4 m of rain a year at Saint-Benoît (windward), 9 m at the Takamaka station, and only 700 mm at Saint-Paul (leeward).

  • Réunion has a volcano whose lava sometimes runs all the way to the sea!

    Larousse says most lava flows of the Piton de la Fournaise come from cracks on its sides and run down the Grand-Brûlé slopes, sometimes all the way to the sea.

    Larousse: most lava flows come from lateral fissures and descend the Grand-Brûlé slopes, sometimes to the sea.

  • The sea near Saint-Denis is warm, about 25 °C on average!

    The German weather service's table for Saint-Denis-Gillot gives an average sea temperature of 25.0 °C, from 23 °C to 27 °C through the year.

    DWD, Saint-Denis-Gillot: mean water temperature 25.0 °C (monthly means 23.0 to 27.0 °C).

Words to know

alluvial fan
a fan-shaped spread of mud, sand and stones left where a river leaves the mountains
cirque
a huge bowl-shaped valley with steep walls
caldera
a large hollow left when the top of a volcano sinks in
windward
the side that faces the wind
leeward
the side sheltered from the wind
agglomeration
a town together with the built-up places that have grown around it

Discovery challenge

  1. Saint-Denis is a city on which island?

    Saint-Denis is the main town of which island in the Indian Ocean?

    Saint-Denis is the main town (chef-lieu) of which volcanic island, 560 km east of Madagascar?

    • Réunion
    • Iceland
    • Cuba
    Show the answer

    Réunion

    Réunion!

    Réunion.

    Réunion.

  2. Which is the tallest mountain on Réunion?

    Which peak, 3,069 meters high, is the highest on Réunion?

    Which summit of Réunion's older volcanic edifice, gashed by three cirques, reaches 3,069 m?

    • Piton des Neiges
    • Mount Fuji
    • Kilimanjaro
    Show the answer

    Piton des Neiges

    Piton des Neiges!

    Piton des Neiges.

    Piton des Neiges.

  3. Which month brings the most rain to Saint-Denis?

    In the German weather service's table for Saint-Denis-Gillot, which is the wettest month?

    Which month has the highest mean rainfall in the DWD table for Saint-Denis-Gillot?

    • March
    • October
    • August
    Show the answer

    March

    March!

    March, with 304 millimeters.

    March, 304 mm.

  4. What covers 40 out of every 100 parts of Réunion?

    What covers 40 percent of Réunion, says Larousse?

    Larousse says what covers 40 percent of the island's area?

    • A national park
    • A desert
    • A glacier
    Show the answer

    A national park

    A national park!

    Réunion National Park.

    Réunion National Park.

Nearby places

Explore next

For parents & teachers

What children will learn

  • Locate Saint-Denis on Réunion, east of Madagascar.
  • Explain what an alluvial fan is and why it can flood.
  • Compare the rain on the windward and leeward sides of a mountain island.
  • Describe how volcanoes built Réunion's peaks, cirques and calderas.

Recommended ages: 3 to 17 · About 15 minutes

Talk about it

  • Why might a city built between two rivers need to plan for floods?
  • Why does one side of a mountain island get so much more rain than the other?
  • Why might a city grow up the gentle slopes behind it?

Try at home or in class

  • Alluvial fan: with a grown-up, pour water and sand down a tilted tray and watch a fan of sand spread out at the bottom.
  • Rain shadow: hold a damp sponge 'mountain' in front of a fan and see which side stays dry.
  • Rain chart: draw a bar for each month of Saint-Denis-Gillot's rain and color the November to May bars.

Key vocabulary: alluvial fan, cirque, caldera, windward, leeward, agglomeration

Where these facts come from

  1. Wikidata , Wikimedia Foundation (CC0 1.0)
  2. Natural Earth vector data , Natural Earth (NACIS) (Public domain)
  3. Saint-Denis (97400) , Larousse encyclopédie
  4. La Réunion (974) , Larousse encyclopédie
  5. Gillot , Larousse encyclopédie
  6. SAINT-DENIS, La Réunion , Encyclopædia Universalis
  7. Réunion: Arrondissements, Communes & Agglomerations , City Population (Thomas Brinkhoff), from INSEE
  8. Klimatafel von Saint Denis-Gillot, Insel Réunion / Indischer Ozean / Frankreich , Deutscher Wetterdienst
  9. File:Saint-Denis vu depuis le belvédère de la Montagne.jpg , Wikimedia Commons
  10. Wikimedia Commons , Wikimedia Foundation (Per file (public domain, CC0, CC BY or CC BY-SA); see each media record)

Checked, not yet human-reviewed. Last updated November 1, 2026. Spotted a mistake? Tell us.

Picture credits
  • Photo: Clémenceau Lauret, CC BY-SA 4.0, via Wikimedia Commons · source · license