What counts as old for an Icelandic horse?

Hi! It depends entirely on the individual, but there are flying-pace world champions who have been over 20 and broken world records.

The thing to remember with horses approaching and past 20 is that they need to keep moving to stay fresh. A longer spell of recovery can be devastating. So with good care and sensible training they can keep going for a long time, especially for forest hacking, as long as you vary the surface, the gaits and the length of the rides, give them enough rest in between, and make sure they also work in a sustainable outline. An older horse can be the best horse there is. I would strongly recommend buying an older one as your first horse, even if you may not get all that many years together.