I am travelling to Tbilisi, and I have a paddle board. Are there any issues with me launching and travelling up the river?
The SUP (Stand Up Paddleboarding) website SUPTrotters has many examples of places in Georgia you can do stand up paddleboarding.
However, the strength, ferocity of rivers, cascades etc, would be worth investigating before launching an expedition on any type of river, anywhere. It may be worth using SUPTrotters to contact other users in Georgia as guides or for further advice or information.