The Koitajoki-Tolvajarvi National Park unites two areas. One of the areas - Koitajoki - is situated close to the Russian-Finnish border, in the special frontier zone, and the Tolvajarvi area is located to the south. The areas are connected by a wide green "corridor", which is a part of a buffer zone around the protected areas. Ruogh image of the local nature is common for Karelia. 160 lakes cover about 10% of the Park's total area.
The natural beauty of Tolvajarvi and adjacent territories is created by a mosaic of lakes, forest, marshland, and eskers formed by deposits of thawed glacier water. Narrow, meandering and overgrown with light pine forest, steep eskers separate nine lakes from one another. The Tolvajarvi area is the most fascinating part of the National Park. Once, three Karelian villages were situated here. In the surroundings of the village of Tolvajarvi, the largest of them, old meadows have preserved. They gradually are overgrowing with juniper, alder, aspen and birch. In the former times selective cuttings were regularly carried out here.
Therefore, today, only small forest areas found in different parts of the Park combine with undisturbed ones.
Mires and bodies of water in Tolvajarvi become rest places for migratory birds in spring and autumn. In May, Whooper Swan and Black-Throated Diver fly here to breed, and their calls can be heard at dusk and at dawn. Gray Crane and Bean Goose nest in mires. Brown Bear and other large beasts of prey, like Wolf, Wolverine and Lynx, inhabit the forestland. This region is the southernmost in Karelia where Forest Reindeer can be met.
The valley of the River Koitajoki differs a lot from the Tolvajarvi area. Its intricately twisting riverbed is fringed with low paludal banks. Many waders, including rare species, choose this place for breeding. Several medium-size lakes are located closer to the border. The village of Kuolismaa is near Koitajoki, where settlements dating from the Stone Age have been found.