There are three cruiser companies offering boats for hire from Carrick-on-Shannon with the widest choice of boats on the river. The river on the Upper Shannon is mostly wide and slow and there are four locks from Athlone to Carrick-on-Shannon and one Lock at the entrance to Lock Key - locks cost €2.50 to pass through at the time of writing. The locks on the upper Shannon are manned and the lock-keepers will be happy to help you through the locks, and offer any advice you need on your destination.
Navigation on the lakes and rivers is easy, there are green and red markers that outline the cruising channels, they're painted white on the side that you need to be on. The markers are accurately marked on the navigation maps that will be on board your boat when you take over and full tuition is provided.
There's free mooring at every town and village along the Shannon and most mooring is within 5 minutes walk of the village or town. Mooring is paid at Athlone as it's supervised, the last time we were there it was €12 for the night including power if required.