The Ruņupe is considered to be one of the fastest rivers in Latvia, as its drop is ~ 3.8 m / km. The winding, small river flows through a deep valley with steep banks. In order to protect its most important natural values – sloping and ravine forests and oak groves, in 1977 there was founded a nature reserve “Ruņupe Valley”, which is located between Mazgramzda and Vaiņode.   There are mixed forests on the slopes and ravines, in which there grow lindens, maples, oaks, white elms, willows and ashes. In some places, springs flow from the steep slopes, and there are small outcrops of conglomerates (cemented gravel), as well as protected habitats. The riverbed is richly covered with boulders of various sizes, creating streams. This nature reserve has protected habitats and great natural diversity. In 2021, fast-flowing rivers and natural sections of rivers were announced “Latvian habitat of 2021”.  In the nature reserves, making campfires and putting up tents is allowed only in places designated and equipped for that purpose.