The Zaō Mountains, commonly called Mount Zaō, are a complex cluster of stratovolcanoes on the border between Yamagata Prefecture and Miyagi Prefecture in Japan. The central volcano of the group includes several lava domes and a tuff cone, Goshiki-dake, which contains a crater lake named "Okama". Also known as the "Five Color Pond" because it changes c…The Zaō Mountains, commonly called Mount Zaō, are a complex cluster of stratovolcanoes on the border between Yamagata Prefecture and Miyagi Prefecture in Japan. The central volcano of the group includes several lava domes and a tuff cone, Goshiki-dake, which contains a crater lake named "Okama". Also known as the "Five Color Pond" because it changes color depending on the weather, it lies in a crater formed by a volcanic eruption in the 1720s. The lake is 360 metres in diameter and 60 m deep, and is one of the main tourist attractions in the area.