Pyhäsalmi, 22 August 1958: the farmer Erkki Ruotanen was digging a new well in his yard when the spade turned up rusty stones. Signs of copper. A mine opened in 1962 and went deeper for sixty years: copper and zinc, a lift at 12 metres a second, and at 1,400 metres a main level with a restaurant, showers, workshops and a sauna, said to be the deepest in the world. Down there the rock keeps the air at 23 degrees and damp before anyone lights the stove.

Mining stopped in 2022. On 14 November 2025 the last pumping station was switched off, and the mine began to fill: about 600,000 cubic metres of water a year, up to fifty years. The whole main level will go under. The sauna is on that level.

The farmer was looking for water. There is plenty.

What is the strangest place you have had a sauna?

Sources: Timo Mäki, "Pyhäsalmen kaivos", Geologi 2008; Wikipedia, Pyhäsalmi Mine; Finnish Wikipedia, Pyhäsalmen kaivos (citing Callio Lab); Yle 15.7.2025 and Yle 2025 (the last pump, 14 November); Helsinki Times; Mining Weekly 15.4.2022.
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