Banja Luka has always been "a paradise valley" with a lot of greenery, water and fruit as described by many travel writers who have visited Banja Luka. Banja Luka is now known for a large number of green areas (parks and tree-lined roads) because of which is called "a city of greenery".
The most common tree in the urban green space is a horse chestnut tree, but there are also linden, plane tree, spruce and many other species of ornamental woody plants. In the city and its vicinity there are three spas (Srpske toplice, Slatina and Laktaši) with mineral water, whose healing properties were used even in the ancient times.
An interesting nature reserve is connected with mineral water sources in Srpske toplice. It is a word about the population of maidenhair fern (Adiantum capillus veneris L.), which is a Tertiary relic, very rear in the continental part of Europe. An especially important nature reserve is the Vrbas River which represents the main watercourse in Banja Luka. Vrbas, with his blue-green colour and landscapes that creates on its way from the mountain Zec to the River Sava, is one of the most beautiful river in Bosnia and Herzegovina. Its tributaries Pliva, Ugar, Krupa, Rekavica, Švrakava, Suturlija and Vrbanja give special beauty to Vrbas.
Cutting its way through the rocks, from Jajce do Banja Luka, Vrbas has created a fantastic canyon where you will find a series of natural rarities. Rapids, waterfalls, cascades, beaches, surrounding rocks, and the wealth of flora and fauna make this region specific. The Vrbas Canyon is the habitat of numerous relict and endemic plant and animal species that represent the specific ecosystem of the canyon. Vrbas leaves the canyon in the city and from the mountain flow and starts its flow through the valley. This river is characterized by rare and precious species of fish in the salmon family, such as brown trout, grayling and salmon, which indicates a very high quality of water and specific fish stocks. In Vrbas, especially in the lower reaches, can be found cyprinid fish species such as chub, carp, barbel, carp, and there are also catfish, bass, perch and bullhead.
Many events and sports competitions are held on the river Vrbas. Special attractions are water sports for which this river provides excellent conditions. Vrbas is a host to many national and European kayak/canoe sport competitions on wild rivers, rafting and fly-fishing. The specificity of the river is also the boat dajak which is named after the pole which serves for pushing of the boat.