A man died after trying to bathe in a hot spring.
This story originally appeared on Time.com.
As surprising as it might be to learn that a human being dissolved completely in water, the scientific reason why some hot spring water is dangerously acidic and other water completely harmless is completely clear. Scientists behind a 2012 study published in the journal Geochemistry, Geophysics, Geosystems laid out the distinction between acidic and harmless water after evaluating water that originated in the Heart Lake Geyser Basin.
Safe and unsafe water for humans originates in the same place deep underground, but separates as it comes to the surface. Some water becomes highly acidic as small microorganisms that live in extreme heat break off pieces of surrounding rocks adding sulfuric acid to the water. When that highly-acidic water bubbles to the surface—through mud pots and fumaroles—it is no longer safe for humans.
Anyone questioning the safety of water at or near a hot spring should look stay on the path and respect boundaries set by the National Park Service.