Nihondaira Grand Pond
Mt. Nihondaira is situated on the border of Mikawa District and the old Muramatsu District of Gosen City. It takes about 4 hours to the top on foot from Yazawa. Nihondaira Grand Pond is the halfway to the top, about 3 hours from Yazawa.
The grand pond is located on high marshland at an altitude of 865m and is 115m in circumference and 1.35m deep. Some small and large masses float on the pond and swamp and rare alpine species inhabit the surrounding area.
The flora is almost the same on the floating mass and swamp; many carex thunbergii, carex morrowii and wichurae are growing.
Among aqueous insects, 2 species (backswimmers and diving beetles) should be especially mentioned because they inhabit the same water zone mingled together, which is a phenomenon not seen in other habitats. Therefore, this area attracts attention as a valuable habitat concerning insect geography.