The archipelago comprises three large islands, Mauritius, Réunion, and Rodrigues, plus a number of volcanic remnants in the tropics of the southwestern Indian Ocean, generally between 700 and 1,500 kilometres east of Madagascar.

It is the remnant of one -or more- large volcanic islands sitting on the Mauritia (microcontinent) which were submerged by rising tides.

Eventually, Saya de Malha, Nazareth and Soudan were completely submerged, Cargados Carajos remaining as a coral atoll.

Piton de la Fournaise, on the southeastern corner of Réunion, is one of the most active volcanoes in the world, erupting last in December 2021.

The plateau covers an area of over 115,000 km2 of shallow water, with depths ranging from 8 to 150 meters, plunging to 4000 m to the abyssal plain at its edges.

The area remained under nominal Portuguese rule until Étienne de Flacourt arrived with a French naval squadron and took possession in 1649.

[5] From 4 June 1735 to 23 March 1746, a single French Mascarene Islands chartered colony under one gouverneur général (governor general) contained Isle de France (now Mauritius), Île Bourbon (Réunion) and Séchelles (Seychelles).

From 3 February 1803 until 2 September 1810 the French colony of Indes-Orientales, under a capitaine général (captain-general), included Réunion and (nominally) the Seychelles.

It is postulated from navigational charts, such as the Cantino planisphere of 1502,[6] that Arab sailors first discovered Mauritius around 975, calling it Dina Arobi (abandoned island).

In 1810, the United Kingdom invaded the island to protect its East India ships coming around the Cape of Good Hope from French pirates.

Under British Mauritius (1810-1968), the island successfully developed as a sugar cane-based plantation economy and colony until independence in 1968.

Tropical cyclones occur occasionally, bringing heavy rain and high winds, and causing erosion and landslides.

[11] The habitats of the Macarenes vary with the islands' size, topography, age, and proximity to Madagascar, the nearest major land mass.

The plant communities are not homogeneous, and comprise at least five fairly distinct vegetation zones that reflect variations in altitude and in moisture regime.

The dry lowland forests are found on the leeward sides of the islands, from sea level to 200 metres in areas with less than 1000 mm of average annual rainfall.

Palms are the dominant trees, including species of Latania and Dictyosperma album, along with the palm-like screw-pines (Pandanus spp.).

Tree genera and families well-represented in the semi-dry forests include ebony species in the genus Diospyros (Ebenaceae), Pleurostylia (Celastraceae), Foetidia (Lecythidaceae), Olea europaea subsp.

Shrubs in the semi-dry forests include several spectacular endemic species of Hibiscus (Malvaceae), Zanthoxylum (Rutaceae), Obetia ficifolia (Urticaceae), and Scolopia heterophylla (Flacourtiaceae).

On Réunion lowland rain forests are found between 750 and 1100 m. They occur in areas with average annual rainfall of 1500 to 6000 mm.

Other plants include bamboos like Nastus borbonicus, numerous species of orchids (e.g., Angraecum, Bulbophyllum) and ferns e.g., Asplenium, Hymenophyllum, Trichomanes, Elaphoglossum, and Marattia fraxinea.

On Mauritius they are restricted to a small area of Montagne Cocotte in the island's southwest, above 750 metres elevation and with average annual rainfall of 4500–5500 mm.

Herbaceous endemic species include Heterochaenia rivalsii (Campanulaceae), Eriotrix commersonii (Asteraceae), and Cynoglossum borbonicum (Boraginaceae).

Another seven families contain 80 or more species each: Poaceae, Apocynaceae, Cyperaceae, Cunoniaceae, Rutaceae, Araliaceae, and Sapotaceae, representing an additional ca.

Most ferns disperse easily via ornithochory of their spores, allowing fairly frequent colonization from Madagascar and exchange among the Mascarene islands.

The extinct dodo, Cylindraspis tortoises, and broad-billed parrots, along with fruit bats, played an important role in dispersing the seeds.

Settlers cleared most of the forests for agriculture and grazing, and introduced many exotic species, including pigs, rats, cats, monkeys, and mongooses.

The islands have five endemic freshwater fish species, all gobies (Gobiiformes) – Hypseleotris cyprinoides, Cotylopus acutipinnis, Glossogobius kokius, Gobius commersonii, and Oxyurichthys guibei.

Cotylopus acutipinnis, which is endemic to Réunion, hatches in the sea before migrating to the rainforest streams where it lives its adult life.

Rodrigues has nearly continuous fringing reefs bounding an extensive lagoon, 7 to 20 km wide, with deep channels.

Among coral reef fishes, wrasses (Labridae), damselfish (Pomacentridae), carnivorous groupers (Serranidae), and surgeonfishes (Acanthuridae) have many species.