The three Sinimäed (Blue) hills — Pargimägi, Põrguaugu Hill and Tornimägi — rise sharply above the surrounding plains and are the most prominent natural elevations in the region. Formed by geological processes during the Ice Age, they create a landscape that clearly contrasts with the otherwise flat terrain of the Viru Plateau.

In addition to its relief, the conservation area is valued for its diverse forests, including species-rich spruce forests, old natural forests and moist deciduous woodlands. Particularly important is the presence of the rare moss species Anomodon rugelii, for which the Sinimäed area represents one of the most significant habitats in Estonia.