The digital rheoplethysmogram was recorded from 10 normal human subjects during the act of ‘simulated diving’, i.e. submersion of the face in a pan full of water. Digital vascular responses to various maneuvers and stimuli associated with simulated diving were also studied. In general, digital vasoconstriction was seen after most maneuvers and stimuli associated with the diving phenomenon (other than placing the face in water itself). The response of the pulse rate was variable, although a decrease was usually seen as much during ‘simulated diving’ without water in the pan as with water. Decreasing the temperature of the water exaggerated the responses to most stimuli. Digital vasoconstriction was produced by audio stimulation (bell) and deep inspiration, whereas a variable effect on pulse rate was produced. The role of psychic factors and ‘orienting reflexes’ in the production of the cardiovascular response to diving are discussed. It is concluded that respiratory, thermal and psychic factors all play a role in the physiologic response to ‘simulated diving’ and that wetness is only a contributing factor.