Tim Holt

Lt. Cmdr. John 'Twill' Twillinger

Audrey Dalton

Gail MacKenzie

Hans Conried

Dr. Jess Rogers

Barbara Darrow

Jody Simms

Max Showalter

Dr. Tad Johns

Harlan Warde

Lt. Robert 'Clem' Clemens

Gordon Jones

Sheriff Josh Peters

Mimi Gibson

Sandy MacKenzie

Marjorie Stapp

Connie Blake

Jody McCrea

Seaman Fred Johnson

Wallace Earl

Sally

Dennis McCarthy

George Blake (lab assistant)

Sarah Selby

Mrs. Simms

Milton Parsons

Lewis Clark Dobbs

Charles Tannen

Seaman Wyatt (Radioman)

Robert Benevides

Seaman Morty Beatty

John Carlyle

Monster Victim

John Close

Deputy Larry

William Forrest

Admiral Greenhouse

Gil Frye

Deputy Scotty

Joseph Hamilton

Other Lock Watchman

Charles Herbert

Boy with Morty's Cap

Byron Kane

Coroner Nate Brown

Ralph Littlefield

Gatekeeper

David McMahon

Patterson

Ralph Moody

Watchman at Lock 57

William Swan

Seaman Howard Sanders

Hal Taggart

Davis - Resort Owner

Mack Williams

Captain Masters

Dan Gachman

Deputy Brewer

Michael Dugan

Clarke

David Duncan

Story

Arnold Laven

Director

Joel Moss

Sound Recordist

Virginia Mazzuca

Production Assistant

Heinz Roemheld

Conductor

Charles Althouse

Sound Recordist

James Dowell Vance

Art Direction

Jules V. Levy

Producer

Augie Lohman

Special Effects

Kerwin Coughlin

Casting

Arthur Gardner

Producer

Lester White

Director of Photography

John Faure

Editor

Heinz Roemheld

Original Music Composer

Pat Fielder

Screenplay

Rudy Butler

Set Decoration

Scotty Welbourne

Underwater Director of Photography

Heinz Roemheld

Music Director

Maurice Vaccarino

Assistant Director

Olga Collings

Hairstylist

Paul Stader

Other

Ted Haworth

Other

Robert H. Crandall

Other

Abe Haberman

Makeup Artist

B. F. Remmington

Sound Recordist

Charles Althouse

Sound Mixer

Paul Eagler

Other

Allen Sloane

Wardrobe Supervisor

Norman Bishop

Technical Supervisor