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Towada-Hachimantai NP, Iwate
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Hachimannuma’s long basin is actually 11 linked steam-explosion craters, not one simple crater. Field mapping found its deepest point reaches 22.4 m beneath the water.
From this lookout you can take in both Hachimannuma and neighboring Gama-numa. Hachimannuma is the largest pond on the Hachimantai plateau, and its water shifts subtly in color with depth.
Snowmelt makes the wetland’s seasons overlap: flowers that waited beneath lingering snow can open alongside later alpine blooms, so spring and early summer may appear together around Hachimannuma.
The bog encircling the lake began forming about 5,000 years ago, and peat has accumulated to 2.1 m. Its soft moss surface is a living landscape built over millennia.
Foot traffic once left 3,770 m² of the Hachimannuma wetland bare. Restoration began in 1993 using local plant seeds; a decade later, researchers documented strong recovery, including hinazakura.
The loop crosses two different bog types: the gently sloping north has snowbed vegetation, while sphagnum moss dominates the south, forming raised hummocks and wet hollows.
Hachimannuma and nearby high-altitude ponds shelter 6 insect species recorded in numbers—3 dragonflies and 3 aquatic bugs. They’re tiny wetland specialists, easy to overlook from the lookout.
