Aerial view of Grand Prismatic thermal spring in Yellowstone National Park, USA. The bright colours are natural. People can be seen walking on the raised trail at the top of this frame giving scale to this large natural feature. The spring is 320ft (approx 100 meters) across and 160ft deep (approx 50 meters). The blue water is a result of light refracting through the clean mineral rich volcanic waters. The yellow and orange hues are chemosynthetic mats (not requiring sunlight) of thermophilic algae and bacteria which assort according to their temperature preferences. The water is heated to 71 Celsius by a magma chamber of the Yellowstone Supervolcano. Diverse thermophilic (heat loving or tolerant) communities include mats of cyanobacteria, algae and eukaryotic faunas. They are researched for their genetic potential and by scientists searching for evidence of life on other planets.