Senjogahara Marshland — Alpine Wetland Plateau

Senjogahara is a 400-hectare highland wetland at 1,400 meters elevation, formed when volcanic lava flows blocked drainage valleys and created a waterlogged plateau. The marsh is covered in grasses, sedges, and dwarf shrubs, crossed by wooden boardwalk trails that allow access without damaging the fragile ecosystem. The landscape is wide-open, almost Scandinavian — low vegetation, distant mountains, big sky.

The main hiking trail is a 5.5-kilometer loop (2 hours) that traverses the marsh, crosses the Yukawa River on wooden bridges, and passes through birch and larch forest. The wetland hosts over 350 plant species and is a critical habitat for migratory birds. In autumn (late September–early October), the marsh grasses turn gold and crimson, creating a landscape of subtle, shifting color. The area is part of Nikko National Park and represents the wild, untouched side of Nikko — no temples, no crowds, just altitude, light, and silence.