The main attraction of the "Ruskeala Mountain Park" is the famous Marble Canyon, which 7 years before the opening of the park was included in the list of cultural heritage of the Russian Federation as an outstanding monument of the industrial culture of Russia in the late XVIII — early XX centuries. The canyon itself is by no means a natural formation — actually it is only framed by the beautiful wild Karelian nature. Since the beginning of the XVII century, development of marble quarries began here, and materials was then used by the Swedish authorities during construction. As a result of the excavation of marble blocks, a huge bowl formed in the ground, which was subsequently filled with groundwater and formed the famous canyon, which today is about 400 meters long and 50 to 100 meters wide in different places.
The sight of the Marble Canyon makes a stunning impression on the viewer: the sheer gray marble walls, and often at a negative angle, go into the turquoise-blue waters of the lake, and create a unique visual effect by their reflection. If you rent a boat, then this impression can be further strengthened by swimming in man-made grottoes and admiring the bizarre play of light, many times reflected from the water and marble walls.
In summer, the park is a favorite training place for divers, who have long appreciated the attractiveness and beauty of flooded quarries, connected by bizarre labyrinths of underwater passages. Moreover, the water here is crystal clear both in the depth and on the surface of the lake, because the park staff regularly clean it of debris and falling leaves.