Japan’s mysterious ‘lake of the gods’ www.bbc.com

Born from a volcanic eruption around 2,000 years ago, Japan’s mysterious Mashu-ko, or Lake Mashu, is rumoured to be one of the clearest lakes in the world.
Because the lake is surrounded by dense fog and 200m crater walls that drop sharply into the water, visiting Lake Mashu’s shores is strictly prohibited by the Japanese Ministry of Environment for safety reasons.
In the Ainu language, Lake Mashu is often referred to as Kamuito, meaning “the lake of the gods”, and locals are known to journey as close to the lake as they can for inspiration during difficult times.
Because it has no significant inlets or outlets, Lake Mashu has remained pristine for millennia, drawing visitors for hundreds of years.
In addition to being known as one of Japan’s most beautiful lakes, Lake Mashu is also among the clearest lakes in the world, with a visibility of 20 to 30m.