The Yarlung Tsangpo Grand Canyon in Tibet is the world's deepest canyon, plunging roughly 5,000 to 6,000 metres at its most extreme and running about 500 kilometres. The Grand Canyon in Arizona is not the deepest or the longest, but at roughly 446 kilometres long, up to 29 kilometres wide and about 1,800 metres deep it remains the largest by sheer excavated volume among canyons that are fully exposed and accessible.
What "Largest" Means When Canyons Are Measured
There is no single ranking of canyons, because "largest" resolves into at least four different questions and each produces a different winner.
- Depth — vertical distance from rim to river. Sounds simple, but which rim? Yarlung Tsangpo's headline figure measures from the summit of Namcha Barwa, a 7,782-metre peak several kilometres from the river. Measured from a nearer rim the number falls sharply.
- Length — how far the gorge runs. Straightforward, except that deciding where a canyon ends and an ordinary valley begins is a judgement call.
- Width — rim to rim. This favours canyons cut into soft, flat-lying rock that erodes back easily.
- Volume — the total rock removed. The most meaningful measure of size, and the hardest to compute, which is why it is rarely quoted.
A further complication is definitional. A canyon is conventionally a steep-sided valley cut by a river through rock. Loosen that and you can include submarine canyons on the continental shelves and subglacial trenches under ice sheets, both of which dwarf anything on the exposed land surface.
Yarlung Tsangpo: The Deepest by a Wide Margin
The Yarlung Tsangpo river runs east across southern Tibet at an altitude above 3,000 metres, then does something remarkable. At the eastern end of the Himalaya it turns hard south through a gap between Namcha Barwa (7,782 m) and Gyala Peri (7,294 m), which stand only about 21 kilometres apart, and drops through the gorge between them before emerging in India as the Brahmaputra.
The river falls roughly 2,000 metres over the length of the gorge. With Namcha Barwa's summit rising nearly 5,000 metres above the water within a short horizontal distance, the relief is greater than anywhere else on Earth outside of a few Andean and Karakoram valleys. The canyon is also extremely remote; sections of it were not navigated or fully surveyed until the 1990s, and the inner gorge remains among the least visited terrain on the planet.
The gorge does more than set a record. It funnels moist air from the Bay of Bengal onto the Tibetan Plateau, creating a corridor of unexpectedly lush vegetation deep into an otherwise arid region — subtropical forest at latitudes and altitudes where it has no business growing. The Brahmaputra's full course from this gorge to the Bay of Bengal is traced in our guide to the Tsangpo of Tibet.
The Grand Canyon and Why It Still Sets the Standard
Arizona's Grand Canyon is neither deepest nor longest, yet it remains the reference point, and for good reasons that go beyond fame.
It is unmatched in exposed volume and in the clarity of what it exposes. The Colorado River cut down through a stack of nearly horizontal sedimentary layers, and because those layers were undeformed the walls read as a clean sequence — around two billion years of geological history laid out in order, from Vishnu Schist at the bottom to Kaibab Limestone at the rim. Very few places on Earth show that much time so legibly.
The cutting itself is recent. The Colorado has done most of the work within the last five to six million years, following uplift of the Colorado Plateau by roughly 1,500 metres. The combination matters: rapid uplift gave the river the gradient to cut, and the arid climate meant the walls eroded back slowly enough to stay steep. In a wet climate the same excavation would have produced a broad valley rather than a canyon.
The scale is genuinely hard to grasp from the rim. The canyon is around 29 kilometres wide at its widest, and the North Rim sits roughly 300 metres higher than the South Rim, cold enough to close under snow for part of the year while the inner gorge runs above 40 Celsius in summer.
The Southern Hemisphere Giants
South America and southern Africa hold canyons that outrank the Grand Canyon on depth while remaining far less visited.
- Cotahuasi Canyon, Peru — about 3,500 metres deep, generally cited as the deepest canyon in the Americas.
- Colca Canyon, Peru — about 3,270 metres, roughly twice the depth of the Grand Canyon. It is far more accessible than Cotahuasi and is best known for Andean condors, which ride the morning thermals out of the gorge.
- Fish River Canyon, Namibia — about 160 kilometres long, up to 27 kilometres wide and roughly 550 metres deep. Widely described as Africa's largest canyon and among the largest anywhere. Its five-day hiking trail is open only in the cooler months, because summer temperatures in the gorge are dangerous.
- Blyde River Canyon, South Africa — about 26 kilometres long and up to 800 metres deep, and unusual among major canyons for being green rather than bare rock, cut into the subtropical Drakensberg escarpment.
- Copper Canyon, Mexico — not one canyon but six major interconnected gorges in the Sierra Madre Occidental, several deeper than the Grand Canyon, with a combined system substantially larger in total area.
The Peruvian canyons illustrate why depth rankings shift. Both Colca and Cotahuasi are cut into a plateau that was itself uplifted to great altitude, so the rims stand at 4,000 metres or more while the rivers run far below. Extreme depth here is as much a product of high starting ground as of aggressive erosion.
Underwater and Under Ice: The Canyons That Break the Rankings
If you drop the requirement that a canyon be dry and visible, the list changes completely.
Submarine canyons cut into continental shelves worldwide, carved by turbidity currents — dense, sediment-laden flows that behave like underwater avalanches. Zhemchug Canyon in the Bering Sea has a vertical relief of roughly 2,600 metres and a volume far exceeding the Grand Canyon's, making it by some measures the largest canyon on the planet. Monterey Canyon off California is comparable in depth to the Grand Canyon and begins remarkably close to shore.
Subglacial canyons are stranger still. Radar surveys under the Greenland ice sheet revealed a canyon system running roughly 750 kilometres from the interior toward the northern coast, up to 800 metres deep — a river valley that predates the ice and has been buried for millions of years. Comparable features have been mapped beneath Antarctica.
Neither type appears on a conventional list, because neither can be stood beside. But on volume of rock removed, both outclass everything on the surface.
Canyons Against Fjords and Rift Valleys
Canyons are often lumped together with two other kinds of deep, steep-walled valley, and the distinction is worth drawing because the formation processes are entirely different.
Fjords are glacially carved, not river-carved, and are drowned by the sea. Because ice is a far broader and blunter tool than water, fjords have U-shaped cross-sections with flat floors, where canyons are V-shaped and narrow at the bottom. Sognefjord in Norway reaches about 1,300 metres below sea level with walls rising over 1,000 metres above it. Fjords also occur only where glaciers reached the coast, which restricts them to high latitudes and a handful of temperate mountain coasts. The full comparison is set out in our piece on fjords versus canyons.
Rift valleys are not erosional at all. They form where the crust pulls apart and a block of land drops between parallel faults. The East African Rift runs several thousand kilometres and is in places far wider and deeper than any canyon, but no river excavated it — tectonics did, and rivers merely occupy it afterwards. A canyon is a hole cut into rock; a rift valley is a gap opened between two pieces of rock that are moving away from each other.
The Ranking, With Its Caveats Attached
Bearing in mind that every entry depends on which measure is used, a defensible top ten of exposed terrestrial canyons runs roughly as follows: Yarlung Tsangpo (Tibet) for depth; Grand Canyon (USA) for exposed volume and accessibility; Cotahuasi and Colca (Peru) for depth in the Americas; Copper Canyon (Mexico) as the largest canyon system by combined area; Kali Gandaki Gorge (Nepal), which by the Dhaulagiri-to-Annapurna measure rivals Yarlung Tsangpo on relief; Fish River Canyon (Namibia); Tara River Canyon (Montenegro), Europe's deepest at about 1,300 metres; Capertee Valley (Australia), slightly wider than the Grand Canyon though far shallower; and Indus Gorge (Pakistan), cut past Nanga Parbat with relief exceeding 5,000 metres.
Any list that presents these as a settled order is overstating its case. The honest summary is that Yarlung Tsangpo wins on depth, Zhemchug wins on volume if submarine canyons count, and the Grand Canyon wins on everything you can actually see from a viewpoint — which is why it keeps the popular title. For how a single river manages to cut a hole this size, our explainer on canyon geography works through the mechanics.
