The nature reserve of the Three Peaks is for the most part covered in rocks, stones, and pebbles. Rock faces and ridges are covered in natural alpine vegetation. The chaffinch and alpine accentor can be seen only in this region.

The Three Peaks Nature Park, of 11900 hectares, extends into the municipalities of Dobbiaco, Sesto and San Candido. The Sesto Dolomites are located on the eastern side of Alto Adige and form the north-eastern mountain range on the Italian side.

Holes in the rock, military paths, fortifications, and sometimes fragments of rusty hand grenades are an impressive testimony of the First World War. During what is often called the mountain warfare of 1915-1918, the front between the Italian army and the Austrian army passed through the Sesto Dolomites.