Hot springs are heated by geothermal heat—heat from the Earth’s interior. In volcanic areas, water may come into contact with very hot rock heated by magma. Hot springs in active volcanic zones may produce superheated water, so hot that immersion can result in injury or death.

A hot spring, hydrothermal spring, or geothermal spring is a spring produced by the emergence of geothermally heated groundwater that rises from the Earth’s crust. While some of these springs contain water that is a safe temperature for bathing, others are so hot that immersion can result in injury or death.

Naegleria (nay-GLEER-e-uh) infection is a rare and almost always fatal brain infection. Naegleria infection is caused by an amoeba commonly found in warm, freshwater lakes, rivers and hot springs. Exposure to the amoeba usually occurs during swimming or other water sports.

Soaking in hot springs can be a great way to naturally detox your skin. Thanks to the high amount of silica in the water, it can also soften rough or dry skin. Plus, the mineral content of sulfur springs has been shown to help persisting skin conditions like psoriasis, acne and eczema.

Most onsen experts don’t recommend showering after a hot spring bath because it reduces the effects of the nutrients and minerals in the water. However, when you have sensitive skin or visit an onsen with strong sulfur or acidic springs you should take a shower to prevent possible irritations.

Examples of thermophilic microorganisms found in hot springs include bacteria in the genera Sulfolobus, which can grow at temperatures of up to 90 °C (194 °F), Hydrogenobacter, which grow optimally at temperatures of 85 °C (185 °F), and Thermocrinis, which grow optimally at temperatures of 80 °C (176 °F).

With such high acidity levels and at such high temperatures, even your skeleton doesn’t stand a chance. Within just a few hours, an entire human body in one of these hot springs will have completely dissolved into nothing.

As soon as you fall into the geyser, your skin would react to the incredibly hot water. Old Faithful in Yellowstone has been measured at 95.6°C (204°F). You would feel an immense amount of pain, and it’s safe to say that this would be the most intense burn you’d ever experienced.

“The consensus among the rescue/recovery team … was that the extreme heat of the hot spring, coupled with its acidic nature, dissolved the remains,” a report said. “Hot springs have injured or killed more people in Yellowstone than any other natural feature,” according to the service.

Grand Prismatic Spring. This hot spring is located in Yellowstone National Park. It is the largest hot spring in the world – it is 300 feet (91 meters) wide and 160 feet (49 meters) deep.

Hot-spring water is usually fairly safe from the standpoint of carrying disease-causing organisms, but some is not (see below under “Stay healthy”), and the surface water that cools a scalding spring to usable temperatures will be prone to the same bugs and pathogens as any other surface water.

The naturally high temperatures of the spring water make the water unsafe for bathing, so think twice before you dip your toes in. Fortunately, there are other options at the park that make it possible to submerse yourself in the therapeutic waters at a safe temperature.

The water issuing from a hot spring is heated by geothermal heat, essentially heat from the Earth’s interior. In general, the temperature of rocks within the Earth increases with depth. The water from hot springs in non-volcanic areas is heated in this manner.

Geysers are also created by water that is heated beneath the Earth’s surface, but geysers do not bubble to the surface — they erupt. The passageway traps the heated water underground, so that heat and pressure can build. …