The golden rule of breathing in diving is to breathe slowly and deeply. This is a breathing technique similar to the ones used while meditating. This is a good exercise for the muscles and heart as it gets the blood pumping and it does not put pressure on the heart. This makes diving a great exercise for the respiratory system.~
The warming up of your body coupled with the slow and deep breaths taken while diving help to reduce blood pressure. Studies show that those who dive regularly are less prone to strokes and heart attacks.~
Diving can get real physical too. An average diver carries around 25kg of diving equipment. All your different muscles also tend to work more underwater due to the resistance of the water. This makes diving a really physical work out.