The caldera
How Big the Ngorongoro Crater Actually Is
Sixteen to nineteen kilometres across, walls up to 600 m high — and the superlative everyone repeats about it is wrong as usually stated.
Check dates and availability ↗Ngorongoro Crater dimensions, and which authority gives which figure
| Measurement | Figure | Source |
|---|---|---|
| Diameter | 16–19 km | UNESCO Man and the Biosphere; Britannica agrees |
| Diameter | About 20 km | Ngorongoro Conservation Area Authority |
| Crater floor area | About 260–264 km² | NCAA, Britannica and UNEP-WCMC agree |
| Wall height above the floor | 400–610 m | UNEP-WCMC; UNESCO gives 400–600 m |
| Rim elevation | About 2,286 m (7,500 ft) | Britannica and the CDC Yellow Book |
| Floor elevation | About 1,700 m | Consistent with elevation modelling and Britannica |
| Age of collapse | Roughly 2–3 million years | NCAA gives 2.5 million; IUGS gives 2 million |
The superlative, stated properly
You will read everywhere that Ngorongoro is the world's largest caldera. It is not, and the claim is easy to disprove: Toba in Sumatra, Yellowstone and La Garita in Colorado are all very much bigger. What makes Ngorongoro exceptional is a narrower and more interesting thing. UNESCO's own geopark designation calls it the world's largest inactive, intact and unfilled volcanic caldera. The International Union of Geological Sciences puts it as the largest unflooded and unbroken caldera, and is explicit that larger calderas exist which either have broken rims or have filled to become lakes. That qualified version is the true one, and it is the more remarkable claim.
A mountain that may have out-topped Kilimanjaro
Before it collapsed, this was a single volcano, and the estimates of its former height are startling. The NCAA describes it as having been nearly the size of present-day Kilimanjaro. The IUGS goes further, suggesting the volcano may have exceeded 5,000 metres before the collapse. What happened next is the definition of a caldera: the magma chamber beneath emptied, the summit lost its support, and the whole upper cone fell inward. Sources put the collapse at roughly two to three million years ago, following an earlier phase of very heavy volcanism around four million years ago in the wider highland field.
The numbers, and why they disagree
Almost every dimension of the crater is published as a range, and the ranges are wide enough to matter. Diameter runs from 16 km to 22 km depending on who you read, because a collapsed caldera is not circular and the answer changes with the bearing you measure along. UNESCO gives 16 to 19 kilometres, the NCAA about 20, and the IUGS 22. The floor area is the figure everyone agrees on, at roughly 260 to 264 square kilometres. Wall height is quoted from 400 to 610 metres, again because the rim is uneven. Where a range exists, this guide gives the range.
Six hundred metres of wall, and what it does
The wall is the reason Ngorongoro looks and behaves the way it does. Rising up to about 600 metres above the floor and enclosing it almost completely, it produces a bowl roughly 260 square kilometres in area with its own microclimate: the rim is moist, misty and forested, while the floor below is open short-grass plain with a soda lake at its centre. It is not a fence, and the animals are not trapped — the herbivore populations do move in and out. But the wall concentrates them, and it is why a single day inside can show you more large mammals in one field of view than weeks elsewhere.
One number that is constantly misapplied
You will frequently see a figure of around 25,000 large animals attached to the crater floor. That number comes from UNESCO, and it refers to the whole Ngorongoro Conservation Area — a property of 809,440 hectares, more than thirty times the area of the crater floor. Applying it to the floor alone overstates the density enormously. The crater is extraordinarily rich in wildlife and needs no inflation. If you see a site quoting tens of thousands of animals inside the caldera specifically, treat everything else on that page with the same scepticism.