Aonuma (Goshikinuma Pond Group)

Aonuma (Blue Pond) is one of the most striking of the Goshikinuma ponds, a colorful cluster of around 30 shallow ponds and marshes formed when Mt. Bandai erupted in 1888 and triggered a landslide that blocked a nearby river. Aonuma’s deep blue color contrasts beautifully with both summer greens and autumn foliage. Plants overhanging the pond appear frosted where they have dipped into the water. This is due to a coating of aluminum silicate, an acidic compound in the water deposited during the eruption. Aluminum silicate is present in other lakes within the Goshikinuma cluster, but to a lesser degree. The pond is too acidic for plankton or fish, but it supports extensive mats of moss called Drepanocladus fluitans.