Psychological stress is stress due to the Scuba diver's reaction to per­ceived "threats" in the environment, including perceived causes of actual body harm, and "threats" to the self esteem. The Scuba diver's beliefs and attitudes play major role in psychological stress, so that the stressor may be imagined as well as real. 

Psychological stress often results from physical stess. For example, a Scuba diver might become very tired during a long swim, triggering a fear that he might not make it to the boat, or, a Scuba diver might miscalculate and run out of air, triggering the fear that he will drown. Overexertion, which can cause a Scuba diver to demand air faster than a regulator can effectively deliver it, can trigger fears of air starvation and suffocation. Any form of physical stress can trigger psychological stress if it triggers fears or anxiety about whether the Scuba diver can cope with the situation. 

Psychological stress can also arise from internal reactions, including task loading (trying to accom­plish too much at once), peer pressure, the percep­tion that a Bali Scuba dive is beyond the Scuba diver's abilities, and the belief that particular hazards exist on the Bali Scuba dive (real or imagined). Psychological stress can even arise when, due to distance traveled or money spent, a Scuba diver pressures himself to Bali Scuba dive when he'd rather not.