Senjogahara Marshland Boardwalk Trail

The Senjogahara Marshland Boardwalk Trail traverses Nikko National Park's largest highland wetland, a former lakebed at roughly 1,400m elevation in Okunikko, Tochigi Prefecture. Hikers typically start at the Akanuma parking area, reached by Tobu Bus from Chuzenjiko Onsen (about 30 minutes, ¥1,000), and follow a well-maintained wooden boardwalk for 5.7km to either Ryuzu Falls or Yumoto Onsen. The route is almost entirely flat with negligible elevation change, making it accessible to a wide range of fitness levels, though the full one-way distance takes 2-3 hours at a relaxed pace with time for photography. The boardwalk surface is elevated timber decking across marsh grassland, with occasional gravel connector paths through surrounding birch and larch forest; there is little shade over the open marsh sections. Key landmarks include the Akanuma information hut at the start, the Izumiya rest area roughly midway, and the Ryuzu Falls viewpoint near the western exit, where the boardwalk connects to the falls' rapids trail. In late May and early June the marsh floods with mizubasho (skunk cabbage) blooms, and in late September and October the grassland turns gold and crimson. There are no water sources or shelters directly on the boardwalk beyond the Akanuma and Izumiya rest huts, so hikers should carry water for the full crossing.