Rowing has long been recognized as the perfect aerobic pursuit, with naturally smooth and flowing movements that don't tax the joints but do boost the heart rate. Now you can take your rowing experience to the next level with the WaterRower Natural rowing machine. Using the same principles that govern the dynamics of a boat in water, the WaterRower Natural is outfitted with a "water flywheel" that consists of two paddles in an enclosed tank of water that provide smooth, quiet resistance, just like the paddles in an actual body of water. As a result, the machine has no moving parts that can wear out over time (even the recoil belt and pulleys don't require lubricating or maintaining). More significantly, the water tank and flywheel create a self-regulating resistance system that eliminates the need for a motor. As with real rowing, when you paddle faster, the increased drag provides more resistance. When you paddle slower, the resistance is less intense. The only limit to how fast you can row is your strength and your ability to overcome drag. And unlike conventional rowing machines, which tend to be jerky and jarring, the WaterRower Natural is remarkably smooth and fluid.