The pond's color can appear to shift between turquoise and emerald green depending on the weather conditions and the angle of the sun.
Substances like allophane and aluminum hydroxide suspended in the water scatter blue light, creating the pond's signature appearance.
The 1888 phreatic eruption that created this pond destroyed several villages and redirected local river systems.
The 'Goshikinuma' name translates to 'Five-Colored Ponds,' though there are actually dozens of smaller ponds in the immediate volcanic debris field.
The pond features a distinct 'heart-shaped' scale pattern on one of its resident koi fish, which has become a popular subject for local folklore and photography.
Bishamonnuma is the largest and most prominent of the Goshikinuma Ponds in the Urabandai lake district of Fukushima. The pond's distinct emerald-blue hue is caused by volcanic minerals from Mount Bandai that reflect sunlight. It serves as the primary gateway to the Goshikinuma Nature Trail, a 3.6-kilometer walking path connecting several differently colored ponds. The pond was formed by the 1888 eruption of Mount Bandai, which created the surrounding swampy terrain and hundreds of other lakes. Visitors can view the pond from a wooden observation deck near the main entrance. Carp and other freshwater fish inhabit the water and are often visible near the surface. The surrounding landscape features a mix of deciduous forests that transition significantly in color during the autumn months. Interpretive signage at the site explains the geological history and the chemical processes contributing to the water's color variation.
The wooden observation deck near the main entrance offers the best elevated angle for capturing the pond's emerald color against the backdrop of Mount Bandai.
Bring a pair of sturdy, comfortable walking shoes if you intend to walk beyond the main observation deck onto the Goshikinuma Nature Trail.
Check the local Urabandai weather forecast before arrival, as visibility and water color vibrancy are best under direct sunlight.
Visit during the early morning hours to avoid the peak tour bus congestion that frequently occurs mid-day.
Avoid rushing through the main deck; many visitors ignore the walking trail which offers far superior, less-crowded views of the smaller, hidden ponds.
The nature trail can be inaccessible during heavy winter snowfall; ensure paths are open if visiting between December and March.
Stay on marked trails to protect the fragile volcanic soil, and do not feed the fish in the pond.
