A medium-sized gadfly petrel with long, pointed wings, long tail, and elastic, powerful flight. Bill is short and thick. Upperparts all dark. Has two color morphs—dark and pale. In pale morph, head and breast dark, contrasting with white belly, creating a hooded appearance. Undertail coverts dark. Dark morph is all dark on belly. In both morphs underwing has pale mid-wing panel across the entire wing.