In Zagreb (and probably lots of other cities; the Sava's decently long), you can walk along the river or bike on the bike path. Saw some guys fishing, but for what, who knows?
This river you will see in your tour of ex.Yugoslovia.You will see it many times in many parts of different countries now.
This river flows through these lands: Slovenia, Croatia, Bosnia and Herzegovina, Serbia. You can see it when you go by bus or car to the park Bundek, or by tram No 6, 7, 8.
This river dividing the Zagreb on main two parts, some kind of old Zagreb and across river the new part of city. Very pleasant to walk alongside
The Sava River doesn’t flow through the centre of Zagreb, so many tourist don’t know that Zagreb has a river. I saw it from the tram, when I visited the Museum of Contemporary Arts in Novi Zagreb.