They consist of three integrated parts: Lower Holes, New Holes, and the Upper Holes. The beauties of the valley are the result of mountain stream erosion. The holes include more than twenty waterfalls.
Strecno Castle towering on top of the massive limestone rock has already existed in the first half of the 14th century. The castle was to safeguard the toll collection at a ford through the Vah river in the region. Nowadays, the castle houses a museum with an imposing exposition and spectacular views from the tower.
The romantic valley is lined with mountain stream.The object of protection is a biologically important area of Mala Fatra with preserved typical Carpathian mountain forests and alpine mountain nature.