Goshiki-numa Ponds — Five Volcanic Crater Lakes in Vivid Colors

Goshiki-numa (五色沼, 'Five-Colored Marshes') is a collection of 30+ volcanic ponds created by the 1888 eruption of Mt. Bandai, whose catastrophic explosion collapsed the northern face and created a debris field that formed these mineral-rich crater lakes. The ponds display extraordinary colors — emerald green, cobalt blue, turquoise, rust-red, and jade — caused by varying mineral content, water depth, and algae concentrations. The most famous are Bishamon-numa (毘沙門沼, deepest at 13m, cobalt blue), Aka-numa (赤沼, 'Red Marsh', iron oxide-stained), and Midori-numa (みどり沼, 'Green Marsh', vibrant emerald from volcanic minerals).

The 3.6km nature trail connecting the ponds takes 70–90 minutes one-way through primeval forest, with wooden boardwalks providing close access to the otherworldly colored waters. Each pond has distinct character — some reflect surrounding mountains like mirrors, others bubble with subterranean gases, and several allow rowboat rentals for on-water exploration. The trail is relatively flat and accessible, making it one of Fukushima's most popular nature walks. Seasonal variations add drama: spring adds cherry and azalea blooms (May), autumn transforms the forest into fiery reds and golds (October), and winter covers the ponds in snow and ice while maintaining their color intensity beneath.