The area around Onuma is one of the oldest natural parks in Japan, where nature has been protected and park facilities have been developed as a Hokkaido provincial park since 1903. On April 17, 1915, Onuma was selected as one of Japan's New Three Views along with Miho no Matsubara (Shizuoka Prefecture) and Yabakei (Oita Prefecture), and in 1957, in support of the movement to elevate Onuma to a national park, a written request was submitted to the Hokkaido prefectural government. In July 1958, the following year, Onuma Park was designated as the 13th national park, and Onuma and Komagatake became a special national protected area.

The 126 islands of various sizes floating in Lake Onuma and the other three lakes add a delicate color to the scenery of Onuma. Some of these islands are connected by arched bridges, and visitors can enjoy walking around the islands from the park square. On the surface of the lake, which is an inlet surrounded by islands, you will find water lilies and other water plants, as well as carp and crucian carp bobbing in the water, their leaves shaking in the air. If you are lucky, you may also see kingfishers flitting about on the surface of the water or squirrels busily nibbling on nuts.

In Onuma National Park, the lakeside areas of Onuma, Konuma, and Junsai-numa turn brilliant colors in autumn. The lakes, colored a brilliant red, and the clear ridges of Komagatake (Mt. Komagatake) show the beauty of nature in all its glory. There are various ways to view the autumn leaves, such as cycling along the path around the lake, canoeing or boating on the lake, or climbing Nipporiyama (elevation: 303 m), located on the west side of the park and offering a panoramic view of the lakeside area. Each offers a different view of the spectacular scenery.

Wakasagi fishing is available during the winter. During December, before the lake freezes over, you can fish from the pier, and from early January to mid-March, you can fish on the ice. Many facilities allow you to go empty-handed and have fun, so be sure to give it a try! *For an extra fee, some facilities will deep-fry the wakasagi you catch.