Japan's Lake Mashu on Hokkaido Island is one of the clearest lakes in the world. It was formed about 2,000 years ago due to a volcanic eruption that resulted in the formation of a caldera. Because of its remoteness and inaccessibility, few visitors come to admire the pristine lake. The image was acquired August 28, 2011, and is located at 43.6 degrees north, 144.5 degrees east. https://photojournal.jpl.nasa.gov/catalog/PIA23679