This case study presents a fictional story in a realistic setting to teach aspects of human cardiovascular and respiratory physiology as they pertain to decompression sickness and its treatment options. Specifically, students learn about the partial pressures of gases in the circulatory system and how they change with depth and altitude. The case relates how Dan and Beth, a couple who operate a charter business for diving expeditions, take six tourists out to dive a shipwreck. When it comes time to ascend, one of the divers cannot be found and Dan must stay behind for the rescue. When he finds the missing diver, there is not enough air left in their tanks to rise slowly and safely decompress. They make it to the surface, but must be airlifted to the nearest decompression chamber for treatment. This case was developed for Masters-level students in biology, but could easily be adapted for an upper-level undergraduate physiology course.