The sooty tern is a seabird of the tern family. It is a bird of the tropical oceans, breeding on islands throughout the equatorial zone. This is a large tern, similar in size to the Sandwich tern. The wings and deeply forked tail are long, and it has dark black upperparts and white underparts. It has black legs and bill. Juvenile Sooty Terns are scaly grey above and below. The Sooty Tern is unlikely to be confused with any tern apart from the similarly dark-backed but smaller bridled tern.