This type of machine provides a smooth action with little wear and tear to the mechanism, and the flywheel itself could help to keep you cool as you work out. It's worth noting that although water rowers aim for a realistic rowing feel, competitive rowers often use air rowers for land training. They tend to be less expensive than water-powered rowing machines, as well.

The sport's governing body is formally known as the "Fédération Internationale des Sociétés d'Aviron" (English translation: International Federation of Rowing Associations), though, the majority of the time, either the initialism "FISA" or the English co-name, World Rowing, which the organization "uses for 'commercial purposes,'"[27] is used to refer to it. Founded by representatives from France, Switzerland, Belgium, Adriatica (now a part of Italy), and Italy in Turin on 25 June 1892,[28] FISA is the oldest international sports federation in the Olympic movement.[29]
When waves run into water moving in the opposite direction, they are slowed, just as if they were approaching a beach. Wave length becomes shorter, wave height higher, and they may break. A good (bad) example of this is an ebb current flowing out of Raccoon Strait into waves coming in from the Golden Gate. Good rough water training, if that’s what you want.
Of the four types of rowing machines or ergometers, water rowers are best at reproducing the sensation of on-water rowing. Their stroke cycles hold true to the dynamics of real paddling, and each stroke is punctuated with a splash! Water rowers have sliding seats to allow full-body cardiovascular workouts. (With cheaper rowing machines, in contrast, the seats don’t move.) These fitness machines tend to feature high quality parts and can last a lifetime.
The rowing machine itself is unlike any other on the market with its patented water filled flywheel. It is hard to exactly copy the action of a scull on the water, but the mechanics of the flywheel spinning in water comes in a close second on dry land. The fact that the water is 800 times denser than air means that there is no need for any extra resistance or dampening that you will find in normal air rowers. The faster you pull, the more resistance is generated giving it infinite variability. However, if you want to be able to practice rowing with a faster stroke, you will have to reduce the amount of water in the tank unlike an air rower where you just have to adjust the baffle.