This image was taken at the Strokkur Geyser in Iceland, just as it begins to erupt. This is a hydrothermal explosion, which occurs when water of extremely high temperatures that is trapped below earth’s surface converts from liquid to steam. Debris, rock, boiling water, and mud are then shot up, every 15 minutes for up to 10 meters in this case. Within the geysers, there are elevated levels of sulfuric acid and hydrogen sulfide gas which causes them to emit a strong smell. This image shows the potential energy of a geyser, because it builds up the properties needed 15 minutes at a time to erupt, then repeats this process again. The circular shape that resembles a bubble about to pop shows the pressure from the heat inside the ground, and a few milliseconds after this image was taken, the pressure was released. The apparent steam throughout the image shows just how hot the water is, and demonstrates the temperature needed for an eruption of this size.