This study was undertaken to evaluate the reaction of vascular system in response to water immersion in divers and non-divers humans. 30 healthy subjects were divided in to two groups, divers and non divers (15 subjects each). The divers were regularly trained in water, while non-divers were irregularly trained. All participants were subjected to immersion in water for 30 minutes. After the end of immersion time, heart rate, cardio vascular assessment, blood pressure (BP), bradykinin, histamine, LA, potassium, and magnesium concentrations were detected in all subjects. We revealed significant decreases in heart rate, blood pressure with significant increases in histamine, bradykinin, potassium and manganese concentrations in diving subjects when compared to non-diving. In conclusion, divers have a superior vascular system which is quickly adapted to immersion in water compared to the non-divers.