From Tom Scott.
Normally, the answer would be no. But in these very limited circumstances, at Iceland’s Blue Lagoon, you can swim in geothermal power plant wastewater, and it’s even healthy: although the marketing material doesn’t usually mention it. Here’s a story about geothermal energy, cheap heat, and how to keep some ducks warm.
Research on Blue Lagoon and a skin condition: https://doi.org/10.1016/S0738-081X(96)00099-5
Filmed safely: https://www.tomscott.com/safe/