Dr. David Reed

Richard Carlson

Acting

Kay Lawrence

Julie Adams

Acting

Dr. Mark Williams

Richard Denning

Acting

Dr. Carl Maia

Antonio Moreno

Acting

Captain Lucas

Nestor Paiva

Acting

Dr. Edwin Thompson

Whit Bissell

Acting

Zee

Bernie Gozier

Acting

Chico

Henry A. Escalante

Acting

The Gill Man In Water (uncredited)

Ricou Browning

Acting

Narrator (voice) (uncredited)

Art Gilmore

Acting

Tomas (uncredited)

Perry Lopez

Acting

Dr. Matos (uncredited)

Sydney Mason

Acting

Luis (uncredited)

Rodd Redwing

Acting

Old Man (uncredited)

James Miller

Acting

The Gill Man On Land (uncredited)

Ben Chapman

Acting