Sphenoid sinus mucocele is a rare cystic lesion. It grows gradually and causes visual disturbances, ocular motility abnormalities and headache due to cavernous sinus compression. Sudden change in sinus cavity volume by a barotrauma may compress a mucocele and precipitate symptoms that may easily be confused with decompression sickness. A diver suffering from vertigo, nausea, blurry vision and hearing loss following uneventful dives is presented in this report. He underwent hyperbaric oxygen treatment for inner ear decompression sickness but later was diagnosed as sphenoid sinus mucocele. A high index of suspicion is necessary to capture rare conditions like mucocele in the differential diagnosis for divers with symptoms suggesting vestibulocochlear origin. To our knowledge, only one sphenoid sinus mucocele case presenting as a diving injury has been previously reported.