Physical stress arises from forces on the Scuba divers body that approach or exceed the body's physical limitations. Causes of' physical stress can include cold, seasick­ness, nitrogen narcosis, fatigue, illness or injury, drugs or alcohol, and discomfort and reduced mobility due to poor equipment fit and adjustment. Whether these cause significant stress depends on the Scuba diver's physique; for ex­ample, a long walk in full equipment stresses someone in good shape less than someone who doesn't exercise regularly.

In cold water. a Scuba diver in a wet suit may develop hypothermia after an extended period. while another in a dry suit may be fine. Stressors that have no affect on a Scuba diver one day may create stress the next: for example, a  Scuba diver may be able to make a long swim without difficulty, yet develop leg cramps the next day due to partial dehydration.