The San is one of the longest and most abundant in water Carpathian rivers in Poland. It arises in Western Bieszczady at an elevation of about 900 m above the sea level in Ukraine. The length of the San is 443,4 km and the basin area is 16 861,3 km 2 of which 14 390 km2 is in located Poland.
The San is the main river of the Bieszczady Mountains where meadows ( połoniny) are typical landscape. https://www.google.pl/search?q=po%C5%82oniny&tbm=isch&tbo=u&source=univ&sa=X&ei=_vejVL7rI8zzUNjFgKAL&ved=0CDgQsAQ&biw=128
The Bieszczady is one of the wildest and unspoilt regions in Europe. You can find here endangered animal and plant species, eg. wolves, European bisons, lynxes, bears and Carpathian deer one of the largest deer species. You can often see predatory birds as well as reptiles and amphibians. The upper course of the river is similar to a rapid mountain stream, the section of about 55 km forms the state border between Poland and Ukraine. Below the Lake Solina the river is much wider by 50-100 meters and shallower and sharply cuts into the valley’s slopes revealing vertically formed shoals of sandstone and slates. The same deposits in the form of sharp rock shoals poke out at the bottom of the river above the water during drought periods. This position of rock layers makes in the river numerous hollows, holes and gullies of different depth which are perfect hiding places for fish. Due to this geological structure of the bottom we can wade in almost the whole body of the river. In summer underwater rocks are covered with plaits of vegetation where numerous insects live which are important food for fish. Cold water which flows out of the artificial lake creates good thermal conditions for salmonids. It is here that a 8 km stretch of catch & release was created only for fly fishing. The San here is abundant in numerous graylings , brown trout, and huchen. Barbless hooks and knotless landing nets must be used on the river, and naturally all the fish must be returned to the water.