Goshikinuma Pond Group
The Goshikinuma (lit., “colorful marshes”), are a cluster of about 30 ponds known for their turquoise, green, and copper hues. Around 300 of these shallow bodies of water formed following an eruption of Mt. Bandai in 1888. The eruption sent tons of debris cascading down the mountain’s northern slopes. The ponds formed in depressions that remained when the debris dammed several valleys.
The vivid, multicolored shades are believed to be caused by chemicals and mineral particles such as aluminum silicate in the water and sand. The colors are also affected by reflections of the surrounding landscape and differences in sediment and vegetation. Some of the ponds are very acidic, due to high levels of sulfates in the water, which is the result of the mountain’s volcanic activity. Some have a pH so low that they cannot support aquatic life.
Geologists believe water filters through to these ponds from lakes at higher altitudes. The Copper Pond (Akanuma) is a crater lake high on the northern slopes of Mt. Bandai. It is thought to be the source of springs that feed some of the ponds and affect their mineral content.
The 90-minute walk along the Goshikinuma Pond Trail passes 10 of these ponds.