Grand Prismatic Spring in Wyoming USA

There's no way Yellowstone National Park's Grand Prismatic Spring could be left off this list. The vivid blue centre of the geyser is surrounded by bands of glorious colour, created by the heat-loving bacteria that live there. From above, the pool looks just like a painting of the sun. With a depth of 164 feet (50m), the spring reaches temperatures of 70°C (160°F).