Himenuma Marsh is an artificial lake that was created by trapping spring water. The name comes from the fact that the lake was stocked with kokanee salmon, which are called himemasu in Japanese. The fish can still be found in the lake to this day. The idyllic, circular marsh is surrounded by primeval forest. Visitors can enjoy relaxing walks around the marsh along a wooden boardwalk that was refurbished in 2020. The 1 km loop takes about 20 minutes to complete, with plentiful opportunities for bird watching along the way. On still, clear days many visitors travel to the marsh to see Mount Rishiri (also known as Rishiri Fuji) reflected in the water, a phenomenon referred to as the “Reverse Rishiri Fuji”. There is also a small rest hut by the marsh, which sells photographs of the abundant nature of Rishiri Island, including flowers and wild birds. The walking trail to the Oshidomari trailhead takes about four hours to complete and is an excellent way to take in the sight of the flowers and wild birds that make up the island’s natural environment. (Please be aware that some routes may be dangerous or too steep for inexperienced hikers. If you become concerned for your safety, please turn back immediately.) Himenuma Observatory lies along the road to Himenuma Marsh and offers a panoramic view of the Rishiri Island coast and the town below.