Discesa del Tevere (Canoeing along the Tiber) sees participants canoeing through the valley of the Tiber, from Citta' di Castello to Rome. The excursion consists of seven stretches of 20-30km each and participants paddle in groups led by experienced canoeists.
Those who prefer can cycle, walk or horse-ride along the route. Anyone can participate by filling out the online form, available on the event's website.
Sources and Copyrights: http://events.frommers.com/sisp/index.htm?fx=event&event_id=102236