The 10 Largest Underground Mines in the World
Underground scale hides itself — no rim to stand on, no hole for the drone shot. But the biggest underground operations move open-pit tonnages through tunnels, using gravity as the primary mining machine. The 2026 giants, ranked by sheer scale of workings and output.
| # | Mine | Scale |
|---|---|---|
| 1 | El Teniente — Chile (copper) | 4,500+ km of tunnels |
| 2 | Grasberg underground — Indonesia (Cu-Au) | The biggest cave complex ever built |
| 3 | Kiruna — Sweden (iron) | ~26 Mt/yr from sublevel caving |
| 4 | Olympic Dam — Australia (Cu-U-Au-Ag) | A four-commodity underground city |
| 5 | Cadia East — Australia (Au-Cu) | Panel caving at bulk scale |
| 6 | Oyu Tolgoi (Hugo North) — Mongolia (Cu-Au) | The new giant, 1.3 km down |
| 7 | Kamoa-Kakula — DR Congo (copper) | Highest-grade major underground |
| 8 | Mponeng — South Africa (gold) | The deepest workings anywhere |
| 9 | Palabora — South Africa (copper) | The cave beneath the pit |
| 10 | Kidd Creek — Canada (Cu-Zn) | Deepest base metals on Earth |
The rundown
El Teniente — Chile (copper)
4,500+ km of tunnelsThe largest underground network ever excavated: a century of continuous caving with new levels still being added below the old ones. A subway system that produces 400,000 tonnes of copper a year.
WIKI →▶︎ YOUTUBEGrasberg underground — Indonesia (Cu-Au)
The biggest cave complex ever builtWhen the superpit ended, Freeport moved the whole operation underground: the Grasberg Block Cave and its siblings now pull ore at open-pit rates entirely by gravity — the largest block-caving program in history.
WIKI →▶︎ YOUTUBEKiruna — Sweden (iron)
~26 Mt/yr from sublevel cavingThe world's largest underground iron mine runs automated trains on a haulage level 1,365 meters down — and is famously relocating the city above it.
WIKI →▶︎ YOUTUBEOlympic Dam — Australia (Cu-U-Au-Ag)
A four-commodity underground cityBHP's South Australian giant is among the largest deposits ever found — top-tier in copper and holding the world's largest known uranium resource, all mined from one sprawling underground.
WIKI →▶︎ YOUTUBECadia East — Australia (Au-Cu)
Panel caving at bulk scaleNewmont's NSW operation proved caving could run at tens of millions of tonnes a year with costs that embarrass open pits.
WIKI →▶︎ YOUTUBEOyu Tolgoi (Hugo North) — Mongolia (Cu-Au)
The new giant, 1.3 km downRio Tinto's block cave in the Gobi is ramping toward a scale that will place it among the world's top copper mines — all of it from underground.
WIKI →▶︎ YOUTUBEKamoa-Kakula — DR Congo (copper)
Highest-grade major undergroundRoom-and-pillar-style mechanized mining in ore so rich the trucks barely believe it — the fastest-growing underground complex on Earth.
WIKI →▶︎ YOUTUBEMponeng — South Africa (gold)
The deepest workings anywhereFour kilometers down, ice-slurry cooling, seismic monitoring around the clock — small tonnage by this list's standards, maximum difficulty by anyone's.
WIKI →▶︎ YOUTUBEPalabora — South Africa (copper)
The cave beneath the pitWhen one of the world's great open pits bottomed out, Palabora undercut it — and the crater walls slumping into the cave became a textbook case studied by every caving engineer alive.
WIKI →▶︎ YOUTUBEKidd Creek — Canada (Cu-Zn)
Deepest base metals on EarthThree kilometers down in the Canadian Shield, still hauling ore up a shaft system that took decades to build — the endurance record of hardrock mining.
WIKI →▶︎ YOUTUBEThe economics underneath all of it: caving methods turn gravity into the cheapest loader ever invented. That's why the next generation of giant copper mines — the ones being permitted right now — are almost all underground.
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Figures are approximate, compiled from public sources as of mid-2026, and rounded for readability. Rankings shift with markets, mergers, and new discoveries. Nothing here is investment, legal, or engineering advice for a specific site — for that, hire an engineer. We know one.