Peer into the transparent depths of Lake Mashu
Lake Mashu is renowned for the crystal clarity of its waters. Because no rivers or streams feed it or flow out from it, silt, algae, and other forms of suspended matter do not cloud the water. Its waters, which consist almost entirely of rainwater, have a deep blue hue so special that it is termed “Mashu blue.”
Fog on the lake
Fog forms close to the surface of Lake Mashu frequently throughout the year. During the peak season from May to October, the lake is wholly visible for an average of 137 days, semi-visible for 54 days, and obscured for 29 days (estimates are based on data from 2008 to 2018). The fog is at its thickest in June and July. During this period, the lake is only completely visible for an average of 15 days. The weather around the lake can transition from bright and sunny to dark and foggy within minutes.
Kamuishu Island
Kamuishu, Lake Mashu’s only island, is a pillar of lava that rises some 240 meters from the lakebed. Only the top 30 meters break through the water’s surface. This visible tip of Kamuishu measures only about 500 square meters.