All Cast
Richard Carlson
Dr. David Reed
Julie Adams
Kay Lawrence
Richard Denning
Dr. Mark Williams
Antonio Moreno
Dr. Carl Maia
Nestor Paiva
Captain Lucas
Whit Bissell
Dr. Edwin Thompson
Bernie Gozier
Zee
Henry A. Escalante
Chico
Ricou Browning
The Gill Man In Water (uncredited)
Ben Chapman
The Gill Man On Land (uncredited)
Art Gilmore
Narrator (voice) (uncredited)
Perry Lopez
Tomas (uncredited)
Sydney Mason
Dr. Matos (uncredited)
Rodd Redwing
Luis (uncredited)