Near the town of Kostomuksha is the territory belonging to the state nature reserve "Kostomukshskiy", founded in 1983. The reserve was included in the Russian-Finnish reserve "Friendship" in 1991. This reserve is located on the border with Finland and experts from Russia and Finland is actively engaged in research and preservation of unique natural complexes in the area.

Particularly valuable are the unique forest reserve, which represent a valuable genetic fund and the ideal northern taiga subzone. Basically the reserve grow pine and spruce, but you can meet and deciduous plants. The average age of the trees around 170-180 years old, but there are also long-lived, their age reaches more than 300 years.

In addition to the forest reserve is rich in lakes and their on site, there are about 250. The most beautiful lake in the reserve on the right is Lake Stone, occupying an area of ​​10 hectares and has in its composition 98 islands islands and many bays and capes. It has long been at the local bank is the settlement of Karels, who left behind a meadow out of plowed fields. In total, on the shores of the lake before Stone was located about 20 villages, their inhabitants to freely communicate with their neighbors - Finnish residents. From the lake of the same name originates river - stone, which runs through the park. This river is relatively small - 25 km, and particularly affects leisure majestic king-threshold in the cliffs.

During the Second World War, the reserve has not been greatly affected by the fighting, but in some places still preserved their consequences.

In Kostomuksha nature reserve inhabited by a large number of endangered and rare birds and animals: otter, northern forest deer, lynx, white-tailed eagle, wolverine, golden eagle, whooper swan, osprey, gray crane. The lakes and rivers of the reserve inhabited by the most prolific in Karelia "kamennoozerskaya" population of grayling, lake-river salmon and whitefish.

Those who wish to get to the natural reserve "Kostomukshskiy" we must remember that for the passage of the protected area to get a special pass. In addition, the reserve is prohibited to gather herbs, seeds, berries and mushrooms, hunting, fishing, debris and damage the flora and fauna. Open fires are allowed only in designated areas.