Lake Mashu is located 11km from Teshikaga Town and 12km from Kawayu Hot Springs. The surface of the lake is 351m above sea level, with a circumference of around 20km, an area of 19.6km2 and a depth of 211.4m at its deepest point. It is the world's clearest caldera lake. The lake is surrounded by 150-350m-high cliffs with an average gradient of 45 degrees - steeper than you'll see around any other lake. Lake Mashu is renowned for its mist, and for the way its water level mysteriously remains the same even though no rivers flow in or out. With almost no impurities, the water of Lake Mashu looks like it has been dyed in indigo. Its deep blue color is so unique that it is called "Mashu blue". The area around Lake Mashu has been designated as a special protected area, even by national park standards, to protect the incredible nature. Untouched by human hands (people are prohibited from entering the immediate surroundings), this beautiful, rugged, mysterious lake amazes everyone who gazes upon it from the various viewpoints nearby.