EMS physicians are likely to encounter patients suffering diving-related injuries during their careers. Diving is increasing in popularity worldwide, and many EMS personnel and agencies participate in rescue-diving activities. EMS physicians and medical directors need not be certified scuba divers but will benefit from developing a fundamental knowledge of dive-related physiology and hazards. EMS physicians should be familiar with the basics of diving physics as it relates to diving physiology, local diving activities, up-to-date medical management, and awareness of the nearest available hyperbaric treatment centers. An understanding of the basic conditions encountered during and after a dive, combined with the knowledge of the dive phase at which an injury occurred and the chief complaint, will help to diagnose and treat an injured diver.