Valleys of Nepal: The Deepest Gorge, Largest Valleys & Hidden Beyuls

Nepal is a country defined by its valleys. Because the land rises from the flat Terai plains near 60 metres to Mount Everest at 8,849 metres within a horizontal span of barely 200 kilometres, the rivers draining the Himalaya have carved some of the deepest and most dramatic valleys on Earth, from broad, fertile bowls that cradle the largest cities to narrow, remote clefts sealed off by high passes and preserved as sacred Buddhist sanctuaries.

This guide is an at-a-glance hub for the country's most important valleys. It covers the two great urban and agricultural valleys of the hills, the Kathmandu Valley and the Pokhara Valley; the Kali Gandaki Gorge, the single most famous 'deepest valley' claim in the world; and a family of high, culturally rich trekking valleys, Langtang, Tsum, Nubri, Rolwaling, Arun, Barun and Limi. For each we give location, districts, elevation, the river that formed it, its geology and its living culture. Two evergreen questions run through the subject, which is the deepest valley in the world and which is the largest valley in Nepal, and both deserve careful fact-checking, because the honest answer in each case is 'it depends on how you measure'.

The Kali Gandaki Gorge is the deep valley of the Kali Gandaki (Gandaki) River in central-western Nepal, running along the boundary of Myagdi and Mustang districts within the Annapurna Conservation Area in Gandaki Province. Its fame rests on a striking geometry: the river passes between two of the world's fourteen 8,000-metre peaks, Dhaulagiri (8,167 m) to the west and Annapurna I (8,091 m) to the east, which stand only about 35 kilometres apart. Where the river runs between them, near Tukuche and Lete, its bed sits at roughly 2,520 metres, some 5,571 metres (18,278 ft) below the summit of Annapurna I and slightly more below Dhaulagiri.

That drop of well over 5,500 metres from ridgeline to riverbed is why the Kali Gandaki is so often called the deepest gorge in the world, deeper by that measure than the Grand Canyon. The claim is genuine but contested: there is no agreed definition of a canyon's 'depth', and by the peak-to-river yardstick the Yarlung Tsangpo Grand Canyon in Tibet, and even Nepal's own Arun Valley, are rivals that some geographers rank deeper. It is safest to call the Kali Gandaki one of the deepest gorges on Earth, very commonly but not indisputably listed as the deepest.

Geologically it is a classic antecedent river: the Kali Gandaki is older than the Himalaya, and as the range rose it kept its course by cutting downward as fast as the mountains were pushed up. It is also a sacred landscape, the world's principal source of shaligram, black fossilised ammonites revered by Hindus as aniconic forms of Vishnu, gathered especially between Damodar Kunda and Kagbeni. The gorge carries an ancient trans-Himalayan trade and pilgrimage route, today the Jomsom-Muktinath section of the Annapurna trekking region.

The Kathmandu Valley is the political, economic and cultural core of Nepal and the largest and most developed valley in the country's hill region. Covering roughly 570 square kilometres at a floor elevation of about 1,425 metres, it spans three districts, Kathmandu, Lalitpur (Patan) and Bhaktapur, in Bagmati Province, ringed by green hills such as Shivapuri (2,732 m), Phulchowki (2,762 m), Nagarjun, Champadevi and Chandragiri.

The valley's origin is written in both legend and geology. Scientists have confirmed that it was once the bed of a large lake, the 'Paleo-Kathmandu Lake', whose fine clay and silt sediments still underlie the city and make the ground prone to strong shaking in earthquakes. Over the Pleistocene the Bagmati River eroded through the southern rim at the Chobar Gorge, draining the lake and leaving the fertile bowl behind. Nepali tradition attributes this to the bodhisattva Manjushri, who is said to have cut the Chobar gorge with his sword to drain the waters.

Culturally the valley is extraordinarily dense: it holds the Kathmandu Valley UNESCO World Heritage Site, inscribed in 1979 (2036 BS), which groups seven monument zones, the Durbar Squares of Kathmandu, Patan and Bhaktapur, the stupas of Swayambhunath and Boudhanath, and the temples of Pashupatinath and Changu Narayan. As the home of the Newar civilisation, it remains Nepal's densest concentration of temples, art and living festivals.

The Pokhara Valley, in Kaski district of Gandaki Province, is the second-largest valley of Nepal's hill region and the country's tourism capital. It lies at elevations from about 600 to 1,300 metres between the Mahabharat range and the high Himalaya, so that from the lakeside the Annapurna massif and the fishtail peak of Machhapuchhre (Machapuchare) rise almost sheer above sub-tropical greenery within a strikingly short horizontal distance.

The valley was shaped by the Seti Gandaki (White Gandaki) River, whose milky, sediment-laden water has carved a network of extraordinarily narrow slot gorges that thread right through the city, in places only a few metres wide, largely hidden below street level. The valley floor is also studded with lakes formed behind natural sediment dams, including Phewa (the largest, at about 742 m elevation), Begnas and Rupa, which give Pokhara its postcard character.

The valley's geology is tied to catastrophic debris flows from the Annapurna and Machhapuchhre slopes, which laid down the thick, easily eroded conglomerate the Seti now cuts through, explaining both its lakes and its slot gorges. Today Pokhara is the gateway to the Annapurna trekking region and one of Nepal's most visited destinations.

The Langtang Valley lies in Rasuwa district of Bagmati Province, about 80 kilometres north of Kathmandu and hard against the Tibetan border, within Langtang National Park, established in 1976 (2033 BS) as Nepal's first Himalayan national park. Formed by the Langtang Khola, a headwater of the Bhote Koshi / Trishuli system, it is a glacially carved trough beneath Langtang Lirung (7,234 m). Its Tamang and Tibetan-Buddhist villages, and landmarks such as Kyanjin Gompa (about 3,870 m), make the Langtang Valley trek the third most popular trek in Nepal after the Annapurna Circuit and Everest Base Camp. On 25 April 2015 (12 Baisakh 2072 BS) the Gorkha earthquake triggered a massive avalanche that buried Langtang village, killing an estimated 300-plus people; the valley has since been rebuilt and reopened to trekkers.

West of Langtang, in Dolakha district, the Rolwaling Valley runs below Gaurishankar (7,134 m) inside the Gaurishankar Conservation Area, just south of Tibet. Carved by the Rolwaling Khola, it is revered in Tibetan Buddhism as a beyul, a hidden valley consecrated by Guru Rinpoche (Padmasambhava) as a place of refuge. At its head sits Tsho Rolpa (about 4,580 m), one of the largest and most closely monitored glacial lakes in Nepal because of the risk of a glacial-lake-outburst flood (GLOF). The high Tashi Lapcha pass (about 5,755 m) links Rolwaling to the Everest (Khumbu) region.

In the far north of Gorkha district, in Gandaki Province, two neighbouring valleys sit within the Manaslu Conservation Area beside the 8,163-metre Manaslu, the world's eighth-highest mountain. The Tsum Valley is a classic beyul, a sacred hidden valley named in Tibetan tradition among the 108 refuges blessed by Padmasambhava. Ringed by the Ganesh and Sringi Himal and watered by the Shiar Khola, it preserves an almost intact Tibetan-Buddhist culture: pilgrims visit caves associated with the saint Milarepa, and in 1920 the community declared the valley a shyagya (non-violence) zone where hunting and slaughter are forbidden. Tsum was closed to outsiders until 2008, which helped preserve its monasteries, mani walls and dialect.

Running parallel along the deep gorge of the Budhi Gandaki is the Nubri Valley, whose name means 'the western mountains'. Its villages, including Samagaun (about 3,530 m), Lho (about 3,180 m), Prok and Bihi, are inhabited by people of Tibetan origin who migrated roughly four centuries ago and still speak Nubri, a Tibetic language with several village dialects. Nubri forms the heart of the Manaslu Circuit trek, which crosses the Larke La pass (about 5,106 m). Together, Tsum and Nubri are among the best-preserved Tibetan-Buddhist landscapes in the Himalaya, precisely because their remoteness shielded them from rapid change.

In eastern Nepal, the Arun Valley cuts through Sankhuwasabha district of Koshi Province, between the Everest (Sagarmatha) and Makalu-Barun protected areas. The Arun River is a major trans-Himalayan river that rises in Tibet, where it is called the Bum-chu or Phung-chu (Chinese: Pumqu), and slices southward through the range as another antecedent river. With Makalu (8,485 m) and Kangchenjunga (8,586 m) towering on either side of its deeply incised bed, the Arun Valley is, by the peak-to-river measure, one of the deepest valleys in the world and a serious rival to the Kali Gandaki's 'deepest' title.

A tributary of the Arun, the Barun River, forms the Barun Valley at the foot of Makalu, entirely within Makalu-Barun National Park (established 1992 / 2048 BS). This glacially sculpted valley is prized for biodiversity, from sub-tropical forest to alpine meadow, and is the approach to Makalu Base Camp over passes such as Shipton La.

In the far north-west, the Limi Valley is the northernmost part of Humla district in Karnali Province, bordering Purang County of Tibet. Its three villages, Halji, Til and Jang (Dzang), sit between about 3,700 and 4,100 metres and follow the Drikung Kagyu school of Tibetan Buddhism; the Rinchenling Gonpa at Halji is traditionally attributed to the translator Rinchen Zangpo in the 11th century. The valley lies on an ancient salt-trade and pilgrimage route toward Mount Kailash, over high passes such as Nara La (about 4,620 m).

Which valley is deepest? Measured as the drop from surrounding summits to the riverbed, the Kali Gandaki Gorge (over 5,500 m below Dhaulagiri and Annapurna I) is the answer most commonly given. But the Arun Valley in the east and the Yarlung Tsangpo canyon in Tibet are measured by some sources as equally deep or deeper, so 'the deepest gorge in the world' is best treated as a strong popular claim rather than a settled scientific fact.

Which is the largest valley in Nepal? Within the hills, the Kathmandu Valley (about 570 km2) is the largest and most populous. Beyond the hills, the Dang-Deukhuri valleys of the Inner Terai in Lumbini Province are frequently called the largest valley in Nepal, and even, in popular but unverified claims, the largest valley in Asia. That superlative should be read with caution: use Kathmandu for 'largest hill valley' and Dang for 'largest Inner Terai valley', and treat 'largest in Asia' as folklore.