The Atlantic sailfish is a metallic blue fish with a large sail-like dorsal fin and a long and pointed bill-like snout. It is dark bluish-black on the upperparts and lighter on the sides (counter-shading). There are about twenty bluish horizontal bars along the flanksThe underparts are silvery white. The tail fin is strongly forked. The fins are bluish-black and the front dorsal fin is speckled with small black spots. The bases of the anal fins are pale.