Akanuma (Copper Pond)

Akanuma, or Copper Pond, is a horseshoe-shaped crater lake on the northern flanks of Mt. Bandai, created by the volcano's partial collapse in 1888. High concentrations of iron hydroxide give the water its deep rust color, and the acidity level is too extreme to support fish or aquatic plants. Fumaroles on Mt. Bandai's visible slopes still emit gas above the treeline. Geologists believe the water seeps downward and resurfaces at the Goshikinuma ponds 300 meters below, where minerals alter each pond's color and chemistry. In winter, a guide can take you across the frozen surface to Yellow Falls, a sulfur-stained frozen waterfall the color of aged gold.