A juvenile loggerhead sea turtle (Caretta caretta) stranded in Gran Canaria, Spain was necropsied. The turtle was underweight, had sunken eyes, and small amounts of crude oil were in the oral cavity. The most significant lesion was a large esophageal diverticulum at the junction of the esophagus and stomach. The diverticulum was full of gas and green mucoid fluid and a diffuse thick yellow fibrinonecrotic membrane covered the mucosa. The lumen of the diverticulum also contained moderate numbers of cephalopods, crustaceans, and anthropogenic debris including crude oil balls, plastics, and fishing lines. Histologically there was a severe diffuse fibrinonecrotic esophagitis. Aerococcus viridanswas isolated from the diverticulum. This is the first report of an esophageal diverticulum in a sea turtle. Although A. viridansis a known pathogen of lobsters and fishes, there are no reports of A. viridansinfection in sea turtles.