In the territory of Gauja National Park (Gauja NP) a wide variety of nature biodiversity is richly represented. The major part of Gauja NP is the Gauja River ancient valley, which makes one of the most unique landscapes.

In the territory of Gauja NP almost all natural ecosystems of Latvia are represented - forests, natural grasslands, bogs, rivers, lakes, as well as geological objects, such as sandstone and dolomite outcrops and caves.

The territory of Gauja NP is rich in forests. Forests take a little less than a half of the total park area. In the Gauja NP almost all forest types are present characteristic for Latvia - both pine and fire-tree forests, relatively broad - oak, asp tree and ash-tree stands, which are specifically characteristic to the ancient valley near to the Sigulda town. In the ancient valley there is also the highest proportion of old forests in Latvia.

In Gauja NP territory approximately 90 natural water bodies are located - lakes, mill-pools and lakes of distributaries.

The most significant bog in the Gauja NP is Sudas bog – in the territory of this bog several rare plant species are found.

In the territory of Gauja NP almost 900 vascular plant species are present, 67 of them are rare and endangered. The Gauja NP territory is inhabited by 149 species of birds and 48 mammal species.

In Gauja NP almost all kinds of bat species are detected. All these species are protected. Bat also was chosen as the symbolic animal of Gauja NP.