Mare Nostrum

Antonio Moreno

as Ulysses Ferragut

Alice Terry

as Freya Talberg

Fernand Mailly

as Count Kaledine

John George

as Servant (uncredited)

Madame Pâquerette

as Doctor Fedelmann (as Mme. Paquerette)

Andrews Engelmann

as Submarine Commander (as André von Engelman)

Hughie Mack

as Caragol (prologue)

Frédéric Mariotti

as Toni - the Mate (as Fredrick Mariotti)

Mickey Brantford

as Ferragut's Son - Esteban (as Michael Brantford)

Apollon Uni

as The Triton (prologue) (as Uni Apollon)