The river Tainionvirta starts from lake Jääsjärvi in Hartola and descends about 40 km to lake Päijänne near Sysmä. The difference in height between Jääsjärvi and Päijänne is about seven meters, and there are six rapids in the river.
The Tainionvirta is a peaceful river, running through fields and forests. Considered one of the best fishing rivers in southern Finland, it has a natural population of umber trout, and lake trout are stocked every year. With easily accessible shores, the river is excellent for either fly or spoon fishing. The season starts early, about March, when the teaniopteris insects start to swarm. The Tainionvirta is also very good for canoeing