A previously-healthy thirty-year old man presented to the Emergency Department at Hawke’s Bay Hospital with central chest pain, following blunt chest trauma whilst SCUBA diving. He was at a depth of approximately five metres, during his ascent, when he was dumped onto a rock by a wave, hitting the left side of his chest. Several hours later, he developed central chest tightness and mild dyspnoea. He had no dysphagia or abdominal pain. Examination findings showed normal vital signs, reduced air entry over left chest wall, and a “crunchy” systolic murmur. He had subcutaneous emphysema around his neck. His trachea was central and non-tender. His abdomen was soft, and non-tender. Blood tests showed a mild leucocytosis, but were otherwise within normal limits. CXR (Figure 1) showed pneumomediastinum, with no obvious pneumothorax. A subsequent computerised tomogram (CT) neck and chest (Figure 2) showed extensive pneumomediastinum, subcutaneous emphysema on both sides of neck, no pneumothorax, no tracheal disruption or lung pathology. He was admitted to the Intensive Care Unit and managed conservatively. He was placed on Optiflow™ Nasal Interface (© Fisher & Paykel Healthcare Corporation Limited, Panmure, Auckland, New Zealand) – which delivers high flow humidified oxygen via soft nasal prongs. Repeat CXR showed resolving pneumomediastinum and he was discharged after three days, with no known complications to date.