Pneumomediastinum is a rare injury that has been documented in both recreational and competitive athletes. It has been reported in a variety of situations, but it is often a result of chest trauma. Repeated and prolonged use of Valsalva's maneuvers is also believed to lead to pneumomediastinum, as was the case with the synchronized swimmer presented here. The condition is self-limited and benign in healthy patients, and oxygen therapy may be helpful. Recommendations for athletes typically promote a gradual return to activity after 7 to 10 days.