Stretched 1,650 km from the Chinese border to the Gulf of Thailand and only about 50 km wide at its narrowest, Vietnam occupies about 331,000 km² on the eastern edge of mainland Southeast Asia, bordering China, Laos and Cambodia and facing the South China Sea along a coastline of about 3,260 km. Mountains cover about 40 percent of the land and level ground less than 20 percent. The country's physical regions are the northern highlands, where Fansipan rises to 3,147 m, the highest point in Indochina; the Annamite Range (Trường Sơn) and the Central Highlands plateaus, which run down the Lao border; a narrow coastal plain; and two great deltas, the Red River Delta in the north and the Mekong Delta in the south. The two main rivers are the 1,149 km Red River, which flows past Hanoi to the Gulf of Tonkin, and the Mekong, about 4,900 km long, which ends in Vietnam. More than 102 million people live there, most of them on the deltas and the coast. The best way to see how the country fits together is to start at the top and walk downhill.
Fansipan and the Hoàng Liên Sơn, the Roof of Indochina
The highest ground in Vietnam lies in the far northwest, in the Hoàng Liên Sơn range between Lào Cai and Lai Châu provinces. Its summit, Fansipan, was first measured at 3,143 m in 1909 and later adjusted to 3,147.3 m, making it the highest mountain on the Indochinese peninsula, hence its nickname, "the Roof of Indochina". The peak stands 9 km southwest of Sa Pa inside Hoàng Liên National Park and has a topographic prominence of 1,617 m. The origin of its name is uncertain; one theory traces it to a local name, Hủa Xi Pan, "the tottering giant rock", another to a Hmong phrase for "azalea mountain", after the rhododendrons that grow on its slopes.
The country below Fansipan is steep and deeply cut. On the Fansipan massif, forest survives above about 1,500 m, gnarled, moss-covered elfin forest takes over between 2,500 and 2,800 m, and bamboo and rhododendrons grow above that. Sa Pa, about 300 km northwest of Hanoi, sits on a plateau with an average temperature of about 15 to 16 °C, and in winter temperatures occasionally fall below freezing. The valleys drain to the Red River, which rises in China's Yunnan province and enters Vietnam at Lào Cai. For a stretch it forms the border with China; then it runs southeast through the mountains toward the midlands.
West of the Hoàng Liên Sơn flows the Black River, or Sông Đà, the Red River's main tributary along with the Lô. Its gorges have been turned into a staircase of reservoirs. The Hòa Bình Dam, a 128 m rockfill dam built with Soviet support between 1979 and 1994, has a capacity of 1,920 MW and was Vietnam's largest hydroelectric plant until the Sơn La Dam overtook it in 2012.
Chư Yang Sin, Da Lat and the Plateaus of the Annamite Range
The Annamite Range, known in Vietnamese as the Dãy Trường Sơn, runs from the northwest down most of the length of the country and carries much of the 2,161 km border with Laos, a line based on the colonial-era boundary and confirmed by treaty after 1975. Most of its crests lie on the Lao side; its highest point within Vietnam is Ngọc Linh, 2,598 m, on the Kon Tum massif. Its northern section is narrow and rugged; to the south it throws out spurs that break the coastal strip into a series of separate compartments. One of those spurs reaches the sea between Huế and Đà Nẵng, and the 21 km Hải Vân Pass on National Route 1 crosses it. The ridge marked the boundary between the kingdoms of Đại Việt and Champa from 1306, and it is still a climate divide: in winter, weather north of the pass may be wet and cold while the south side stays warm and dry, sheltered from the cold northwesterly winds.
Further south, the range broadens into the Central Highlands, or Tây Nguyên, a series of plateaus from Kon Tum and Pleiku to Đắk Lắk, five of them fairly flat and covered in basalt soil. The highlands hold about 16 percent of Vietnam's arable land and 22 percent of its forested land. Their basalt soils made them the centre of the coffee industry, which the French began developing in Đắk Lắk in the 1920s and which grew again after the Đổi Mới reforms; coffee is now second only to rice in the value of Vietnam's agricultural exports.
At the southern end of the range stands the Đà Lạt Plateau, also called the Langbiang or Lâm Viên Plateau, where several peaks pass 2,000 m and the highest, Chư Yang Sin, reaches 2,442 m. The city of Da Lat, at about 1,500 m, has a highland climate that earned it the name "City of Eternal Spring" and supplies much of the country with vegetables, flowers and tea. Its montane rainforests are the Southern Annamites ecoregion, and the Langbiang Biosphere Reserve records some 1,940 plant species.
Limestone Country from the Đồng Văn Plateau to Hạ Long Bay
A different kind of upland covers the far north and much of the north-central interior: limestone, dissolved by tropical rain into towers, sinkholes and caves. On the Chinese border, the Đồng Văn Karst Plateau is a landscape of bare ridges and steep escarpments crossed by National Highway 4C. Between the towns of Đồng Văn and Mèo Vạc, in what was Hà Giang province and is now part of Tuyên Quang, the road climbs to about 1,500 m at the Mã Pí Lèng Pass. Lookouts near the crest face the Tú Sản canyon, where the Nho Quế River runs through a narrow gorge under near-vertical cliffs; at about 800 m it is the deepest canyon in the Đồng Văn Karst Plateau Geopark, a UNESCO Global Geopark since 2010. The road itself, the "Happiness Road", was completed in the mid-1960s to connect the plateau with Hà Giang town.
Further south, where the country is at its narrowest, the same kind of rock forms Phong Nha–Kẻ Bàng National Park, a UNESCO World Heritage Site near the Lao border, formerly in Quảng Bình and now in Quảng Trị province. It protects one of the world's two largest karst regions, with about 300 caves; a 2009 survey put the known length of its cave system at about 126 km. The same survey, by British and Vietnamese cavers, explored Hang Sơn Đoòng, whose entrance a local man, Hồ Khanh, had found in 1990 while searching for agarwood. Sơn Đoòng has the largest known cave passage in the world by volume, estimated in 2009 at 38.5 million m³, with a fast-flowing underground river. It formed in soluble limestone between two and five million years ago.
At the northeastern coast the limestone finally reaches sea level. Hạ Long Bay covers about 1,553 km² and holds 1,969 islets, most of them limestone; its core zone of 334 km² alone has 775. The rock took shape over some 500 million years, and the karst towers have been sculpted over about 20 million years of wet tropical climate. The bay is a UNESCO World Heritage Site and continues northeast into Bái Tử Long Bay and southwest to Cát Bà Island.
The Red River Delta and the Dikes of Hanoi
Where the Red River leaves the mountains it spreads across a flat, triangular delta of about 15,000 km², shared with the Thái Bình River. It was once an inlet of the Gulf of Tonkin, gradually filled by river sediment, and the whole plain is no more than 3 m above sea level, much of it 1 m or less. The Red River carries so much reddish silt that its water looks red-brown, and with its tributaries it discharges an average of about 4,300 m³ of water a second. In flood, the high-water mark can stand 14 m above the surrounding fields in places.
For centuries people have lived with that risk by building dikes and canals, a system that has made double-cropped wet rice possible across about half the delta. It is the ancestral home of the ethnic Vietnamese, and although it is the smallest of Vietnam's regions by area it has the largest population and the highest density. Hanoi, the capital, stands on the Red River in the delta, and its riverside districts depend on the same dikes.
The Mekong Delta and the Cà Mau Peninsula, Vietnam's Lowest Ground
The lowest land in the country lies at the southern end, in the Mekong Delta. The Mekong rises on the Tibetan Plateau, runs through China, along the borders of Myanmar and Thailand, and through Laos and Cambodia, and splits just south of Phnom Penh into two branches, the Tiền and the Hậu (known in Cambodia as the Bassac). In Vietnam they fan out into a network of distributaries, and Vietnamese call the river Sông Cửu Long, the "Nine Dragons River". The delta covers about 40,000 km², nowhere more than about 3 m above sea level, and is crossed by a maze of canals.
The river still builds this land. An official Vietnamese estimate puts the sediment it deposits at about 1 billion m³ a year, nearly 13 times the Red River's load, and the delta's coast advances roughly 60 to 80 m into the sea each year. About 10,000 km² is planted with rice, making it one of the world's major rice-growing regions. Its annual flood is tempered upstream by the Tonlé Sap in Cambodia, a lake that swells to as much as 10,000 km² when the Mekong backs up into it and releases the water as the flood subsides. After the provincial mergers of 2025, the region is made up of the provinces of Đồng Tháp, An Giang, Vĩnh Long and Cà Mau, and the city of Cần Thơ.
At the very bottom of the country, the Cà Mau Peninsula is a low triangle built almost entirely from Mekong deposits and lying on average about 2 m above sea level. Toward its tip the rice fields give way to dense mangrove swamp between the Gulf of Thailand and the South China Sea. From Fansipan to Cà Mau, the country descends more than 3,100 m in roughly 1,650 km. For the lowest step in detail, see our guide to the Mekong Delta; the capital's river setting is covered in Hanoi, Vietnam's capital, and the monsoon seasons that shape all of these landscapes are explained in the climate of Vietnam.