Turns out overweight scuba divers are being urged to shed pounds to avoid an underwater heart attack. Cardiac issues are now a leading factor in diving fatalities. Divers who learned to dive years ago and who are now old and overweight with high blood pressure and high cholesterol are at increased risk of dying said study author Dr Peter Buzzacott. People who pay to go diving must learn skills and theory and be screened for fitness. After that initial screening certification to scuba dive lasts for life. This is where the researchers see an increase in risk. It's not commonly