Self-contained underwater breathing apparatus (SCUBA) diving is an ever-growing sport, and despite a myriad of technological advances to improve safety, it remains dangerous. Providers of medical care for SCUBA divers must have an understanding of diving physiology and potential medical problems that can occur. SCUBA diving also can take participants to remote areas, so being properly prepared for potential emergencies can make a significant difference. The following is a review of diving physiology and the medical problems that can occur in SCUBA divers, along with some suggestions as to how to prepare for a SCUBA excursion.