Madagascar ranks as the fourth largest island in the world, measuring 587,041 square kilometers. The Mozambique Channel separates the island from mainland Africa by a minimum width of 400 kilometers at its narrowest point. The island formed through continental drift when it separated from the Indian subcontinent approximately 88 million years ago, moving to its current position in the Indian Ocean roughly 20 million years ago. The island stretches 1,580 kilometers from north to south and reaches 580 kilometers at its widest east-west point.
The Central Highlands, called Hauts Plateaux locally, dominate the interior geography at elevations between 800 and 1,800 meters above sea level. This plateau runs roughly north-south through the island's center and covers approximately one-third of Madagascar's total land area. The highlands divide the island into distinct eastern and western regions with markedly different rainfall patterns and ecosystems. Antananarivo, the capital city, sits at 1,280 meters elevation within these highlands. The plateau consists primarily of laterite soils colored deep red from iron oxide content, visible throughout the region where erosion has exposed underlying geology.
The Tsaratanana Massif contains Madagascar's highest peaks in the northern highlands. Maromokotro, the country's highest mountain, rises 2,876 meters above sea level within this massif. The Ankaratra Massif, located south of Antananarivo, reaches 2,643 meters at its highest point, Tsiafajavona. The Marojezy Massif in the northeast rises to 2,132 meters and features steep granite peaks that receive over 3,000 millimeters of annual rainfall. These mountain systems create microclimates and serve as water sources for major river systems flowing both east and west from the central divide.
The Tsingy de Bemaraha formations in western Madagascar represent one of the island's most distinctive geological features. These limestone karst landscapes consist of sharp vertical pinnacles formed through millions of years of erosion. The Tsingy de Bemaraha National Park, designated a UNESCO World Heritage Site in 1990, covers 1,575 square kilometers. The word "tsingy" derives from the Malagasy phrase meaning "where one cannot walk barefoot." Some limestone needles reach 70 meters in height. The Ankarana Reserve in northern Madagascar contains additional tsingy formations covering 182 square kilometers, along with cave systems that extend for dozens of kilometers underground.
The Isalo Massif in south-central Madagascar forms a Jurassic-period sandstone plateau that rises 800 to 1,200 meters above sea level. The massif covers approximately 820 square kilometers within Isalo National Park. Water and wind erosion over 165 million years created canyons, natural pools, and rock formations throughout the plateau. The sandstone varies from white to deep orange depending on mineral content and oxidation. Natural springs emerge where water filters through porous sandstone and hits impermeable rock layers, creating oases in the otherwise arid landscape.
Madagascar's river systems flow primarily east or west from the central highlands, with no navigable rivers connecting the interior to either coast due to rapids and waterfalls. The Mangoky River extends 564 kilometers, making it the longest river in Madagascar. It flows westward from the highlands to the Mozambique Channel south of Morondava. The Betsiboka River flows 525 kilometers northwest to Mahajanga, carrying massive sediment loads that color the water deep red and have built a delta extending into the Mozambique Channel. Satellite imagery shows the Betsiboka delta's red sediment plumes spreading tens of kilometers into the ocean. The Tsiribihina River runs 525 kilometers from the central highlands to the west coast, passing through varied terrain including gorges, rapids, and lowland forests before reaching the Mozambique Channel near Belo sur Tsiribihina.
The eastern coastal plain extends roughly 10 to 20 kilometers inland from the Indian Ocean to the base of the escarpment that rises to the central highlands. The Malagasy Coastal Plains receive direct hits from cyclones and trade winds, creating the wettest region on the island. This narrow plain features nearly continuous tropical rainforest where not cleared for agriculture. The escarpment rises sharply from the coastal plain, climbing 800 to 1,200 meters over short horizontal distances. The western coastal plains extend much farther inland, reaching 100 to 200 kilometers in width in some areas. These plains experience distinct wet and dry seasons, supporting deciduous forests and savanna ecosystems markedly different from eastern rainforests.
Nosy Be, an island off Madagascar's northwest coast, covers 312 square kilometers and reaches 455 meters elevation at its highest point, Mont Lokobe. The island sits approximately 8 kilometers from the mainland across a strait. Hell-Ville, also known as Andoany, serves as Nosy Be's main town and port. Volcanic activity formed Nosy Be, though no active volcanoes remain. Île Sainte-Marie, called Nosy Boraha in Malagasy, lies parallel to the northeast coast approximately 7 kilometers offshore. This narrow island extends 57 kilometers in length while measuring only 5 kilometers at its widest point. A natural harbor protected by offshore reefs made Île Sainte-Marie a base for pirates during the 17th and 18th centuries. Nosy Mangabe, a 520-hectare island in the Bay of Antongil near the northeast coast, rises steeply from the ocean to 332 meters elevation and maintains protected rainforest.
Madagascar's climate divides into two principal seasons: the hot rainy season from November through April and the cooler dry season from May through October. The east coast receives rainfall throughout the year from trade winds that pick up moisture crossing the Indian Ocean. Toamasina on the east coast records over 3,000 millimeters of annual rainfall. The central highlands experience moderate temperatures due to elevation, with Antananarivo averaging 18.7 degrees Celsius annually. The western and southern regions receive significantly less rainfall, with some areas receiving under 500 millimeters annually. Toliara in the southwest averages only 364 millimeters of rain per year, creating semi-arid to arid conditions.
Tropical cyclones strike Madagascar regularly between December and March, with the east coast and northern regions receiving direct hits most frequently. The island experiences an average of 1.5 to 2.5 cyclone landfalls per year based on data from 1911 to 2010. Cyclone Gafilo in March 2004 produced winds exceeding 230 kilometers per hour and killed 237 people according to official reports. Cyclone Enawo made landfall in March 2017 as a Category 4 equivalent storm with winds of 230 kilometers per hour, affecting over 430,000 people. The storms typically weaken as they cross the island but still bring destructive winds and flooding to the central highlands before exiting into the Mozambique Channel.
Temperature variation depends primarily on elevation and distance from the coast. Coastal areas maintain relatively stable temperatures year-round, with Toamasina averaging between 23 and 27 degrees Celsius monthly. Antananarivo at 1,280 meters elevation experiences cooler temperatures, particularly during the dry season when June and July average 13.8 degrees Celsius. The southern highlands occasionally experience frost during the dry season, with recorded temperatures dropping to -8 degrees Celsius at elevations above 2,400 meters. The western lowlands experience the highest temperatures, with Morondava commonly reaching 35 degrees Celsius during the hot season.
The southeast coast represents Madagascar's wettest region, with some areas receiving over 3,500 millimeters of rainfall annually. The Masoala Peninsula in the northeast receives similar rainfall totals due to its exposure to trade winds and cyclones. Cape Masoala, the easternmost point of the peninsula, extends into the Indian Ocean and experiences constant moisture from onshore winds. By contrast, the southwestern region exists in a rain shadow created by the central highlands blocking moisture-bearing winds from the east. The area around Toliara receives sparse, unreliable rainfall and supports xerophytic vegetation including endemic baobab species and spiny forests.