Swimming is in many respects, is good for health. The sport brings in the cool water on the metabolism trot. It is responsible in particular with the relation to the air higher thermal conductivity of the water: The body loses heat to the water, making the metabolism work more closely in order to compensate for the loss of heat. The immune system is strengthened so that it will be less susceptible to colds and other diseases.
The water exerts pressure on the blood vessels. Transporting more blood to the heart. This leads to a larger stroke volume, ie it will be more blood per heartbeat pumped. The heart needs to beat slower, as the pulse decreases. Also, the lung function improves in regular swimming training.
When the entire body moves in the water, the water body fights against the resistance. This makes for a good swimming muscles. The water also slows down the resistance movements. Sudden abrupt movements in the water will not in any way benefit you, risk of injury is in comparison to other sports is much lower. Another big plus point is that swimming makes the joints, tendons and ligaments barely stay. This is due to the buoyancy of the water. When you swim, you only weigh about ninety percent of the weight outside of the pool. Especially for overweight people swimming is therefore optimal way to remove all excess pounds.
Not quite irrelevant, however, is the choice of life style. Most prefer, or have never learned anything other than the breaststroke. Breaststroke, however, is in some respects worse than, for example, crawl or backstroke. When performing the breaststroke, it keeps most recreational swimmers permanently on the water surface. This can cause problems in the neck and neck area. Furthermore, the leg blow irritate the knee joint. It is better than crawl, dolphin style and back stroke, with the first two but not so easy to learn.