Based on a law passed on 21 December 1956, a decision was made to establish two new nature parks and seven national parks in Finland. One of these was Oulanka National Park, which was opened in 1957. In the first year, a small allocation was used for restoring campsites and signs, and for the purchase of equipment. In 1958, the management of the park was transferred to Metsähallitus.
In the beginning of 1966, the prominence of Oulanka National Park grew due to the opening of the Oulu University Research Station at Oulanka.
In the Great Partition started in 1951, the valuable Kitkanniemi area remained in the ownership of jointly owned forests formed by the owners of the shareholding estates. This was a poor decision for nature conservation. However, Kitkanniemi was attached to the national park in 1989 through an exchange of land between the state and the partnership of the jointly owned forest. Previously, a large aapa mire area in Salla had already been attached to the park.
Along with these attachments, Oulanka National Park gained valuable swamp and forest areas. The national park now also included the rugged canyon of River Kitkajoki, all the way from its lower part to the fork of River Oulankajoki, and the gorges of Juuma. The most significant sights of River Kitkajoki area, Myllykoski rapid, Aallokkokoski rapid, Jyrävä waterfall, and the Pieni Karhunkierros hiking trail, are now located within the national park.
The 1895 book Veneellä poikki Suomenniemen – Seikkailuja Pohjanmaan vesillä ja saloilla (Across the Finnish peninsula by boat – Adventures on the waters and in the backwoods of Northern Ostrobothia) includes a tale about shooting rapids in Kuusamo. The arrival at Jyrävä waterfall had been a great experience: “The roar from the bottom of a rock cavity sounded like a distant thunder. You immediately realized that what was ahead was no ordinary rapid. The earth also seemed to shake underfoot, even though the foundation should have been solid, being a hard and rocky mountain. After struggling down a steep bank through a dense forest, we came to a waterfall that will not be soon forgotten.
The appearance of the waterfall is magnificently beautiful: the extraordinarily high and steep rock walls on both sides of it, a lush coniferous forest on top of the cliffs. Watching the water in Jyrävä fall about 10 metres over a total distance of 25 metres forming two rapids, you can guess how fast it goes, with what force it rushes against the rocky walls and the river bottom.”