Your heart is like an engine. When you dive, your body becomes exposed to pressure. As a result, blood ‘travels’ from the vessels in your leg to the vessels in your chest. It doesn’t require a lot of imagination to see your blood volume release with your chest. It means that your heart is taking in a larger volume of blood. Hence, your four heart chambers ‘become larger’ and there’s a slight increase in your overall blood pressure. Your body is equipped with so-called baroceptors. They act as sensors that detect a change in your blood pressure. 

The water’s thermal conductivity  is high. It means that your body loses more heat when you're in the water than when you're in dry air. One psycho-somatic effect dictates that you will feel more comfortable at a given air temperature than when you're in water of the same temperature. 

As a result of your body losing heat, your blood vessels tend to ‘narrow’. Now this will send more blood to your heart. This increases the pressure and makes your heart pump more blood. With your blood pressure raising, your heart has to work harder to maintain an adequate blood flow of blood throughout your body.

When you are scuba diving you breath air under increased pressure. It affects your circulatory system and your heart. The increased levels of oxygen cause what is called ‘vasoconstriction’ increase your blood pressure and reduce your heart rate and heart output. 

Diving & Breathing 

Does this beg the question whether diving is good for you or not? The answer is yes. Diving is good for your health. Diving is very rewarding in an emotional and physical manner. One rewarding aspect is your way of controlled breathing. This deep slow breathing has a soothing and calming effect and even reduces the risk of a lung-expansion injury. And this is not the only benefit. Controlled breathing increases your lung capacity. Divers would probably be very good didgeridoo players!

Diving & Fitness

Scuba diving on a regular basis steadily improves and maintains your general fitness and stamina levels. Why? Well first of all exercising in water is very effective due to the natural resistance water has against our bodies. Using your legs to fin at depth is great exercise and the sensation of being weightless makes it feel almost effortless. It has been scientifically substantiated that any form of exercise improves cardio-vascular performance and that translates into a reduced risk of heart attacks, strokes, circulatory problems and ailments in general.