Aquatic immersion has been reported to produce a significant number of physiological changes in blood pressure, heart rate variability (HRV), autonomic nervous system (ANS), and core temperature in young healthy subjects. The purpose of this study was to examine the impact of water immersion in younger and older populations, determining whether there are age related differences for ANS regulation measures in cool, neutral and warm water. Vitals and ANS measures were collected from two samples representing different age-groups in the general population. It was found that water immersion produced a significant number of important physiologic responses such as decreased blood pressure and increased SVB during the warm water cycle. These changes are important components of ANS bioregulation and clearly seem to be influenced by water temperature during immersion. There was a statistically significant relationship between ANS activity manifested by heart rate variability and water temperatures.