Jezerka is a national nature reserve in the Krušné Mountains and it is one of the most valuable areas in the mountains. During the Quaternary period the rocky projections started weathering, creating peaks, frost-riven cliffs, rocking stones, rocks, fissure caves and a scree of boulders on the slopes of the hills.

In 1969 this location was declared a national nature reserve, named Jezerka, and it covers 130 hectares. The forests are also protected by the nature reserve. You will find that at the lower altitude the forest is usually mixed, but the higher you go the forest changes and you will soon be surrounded by mostly beech trees, at the very highest places there are only beech trees. The ruins of Žeberk Castle can be found in the reserve and below the ruins you might notice that the wood is a mixture of lime, oak and beech trees. The oak trees growing on the sunny slopes of the hills are very old, their estimated age being 250 years. In some areas the beech woods have the character of primeval woods. Many interesting and rare plant species grow in this area. It has also become a home to many rare species of birds, reptiles and amphibians. In the southern part of the Jezerka National Reserve you will find the state protected Žeberská lime tree that is the oldest tree in the region of Most. Professionals estimate that the lime tree is 750 years old.