Myllykoski rapids of the River Vantaanjoki is a nice place to visit even if you're not interested in fishing. However, this popular fishing spot is strictly regulated and you need special licences (in addition to the normal fishing permit). There are a couple of bridges over the river, one with stone pillars and one lighter. There's also a place to make a fire and grill those sausages you brought with you because you didn't want to go home hungry in case you didn't catch any fish.
The links I've provided are in Finnish but give the contacts where to get the necessary permits and list the rules.
Equipment: Fly fishing permitted only