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There Is A Lake Under A Volcano That Is Boiling Acid

Kawah Ijen's lake is pH 0.5 — and burns blue at night.

Reviewed by the CurioVault curator · 8 October 2026 · Editorial standards

There Is A Lake Under A Volcano That Is Boiling Acid — AI illustration
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Kawah Ijen volcano in Indonesia has a 1km wide turquoise lake with pH 0.5 — as acidic as battery acid, dissolving metal. Sulfur gases ignite on contact with air, creating electric blue flames up to 5m high at night, visible for miles. Miners carry 90kg sulfur blocks through the flames without masks. The most hostile lake on Earth that looks like paradise.

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