Some ears ago I bought a water rower, and it really is great. Close your eyes and think you'r eon a river.
Antony Wilton agrees with me, so I've included his article "Water Rower, Like A Cruise Down The River Without Getting Wet" on http://www.sportandme.com:
http://www.sportandme.com/docs/sports/rowing/guide/water_rower.html
