It is no secret that rowing machines can give you a good workout. If you want to get a more realistic water-rowing experience, you may want to give the Dynamic S6 Laguna Edition AR Fluid Rower a look. It replicates the feel and sound of real water-rowing and offers 16 levels of resistance.
This rower measures 31.9L x 83.5W x 40.2H in. It has a max weight capacity of 330 lbs. Not cheap though.