One of the world’s largest hot springs, Grand Prismatic Spring is located in the USA’s Yellowstone National Park. Explorers gave the spring its name in 1871 after witnessing its incredible prism of colours. Measuring 113 m (370 ft) wide and 37 m (121 ft) deep, it releases 2,120 litres (560 gallons) of water a minute.
The kaleidoscope effect is caused by colourful bacteria, which thrive in these superhot springs. In the blue centre is near-boiling water. This gradually cools across the spring’s surface, and as the temperature changes, different types of bacteria are able to survive. The bacteria living in different parts of the spring are brightly coloured, giving Grand Prismatic its characteristic rainbow rings.