In Ljubljana we have two mayor rivers, Sava and Ljubljanica. Ljubljanica is perfect for kayaking from October till the end of May. During summer there are so many mosquitoes and biting horse flies, it is not pleasant to be around at all..but still if you don't have any other options for paddling and you want it, you may go with the flow in town--no insects there.
Drobtinka.
Yeeey I have a visitor, there were so many dragonflies .