Bradford Dillman character Paul Grogan
Heather Menzies character Maggie McKeown
Kevin McCarthy character Dr. Robert Hoak
Keenan Wynn character Jack
Dick Miller character Buck Gardner
Barbara Steele character Dr. Mengers
Belinda Balaski character Betsy
Melody Thomas Scott character Laura Dickinson
Bruce Gordon character Colonel Waxman
Barry Brown character Trooper
Paul Bartel character Mr. Dumont
Shannon Collins character Suzie Grogan
Shawn Nelson character Whitney
Richard Deacon character Earl Lyon
Janie Squire character Barbara Randolph
Roger Richman character David
Bill Smillie character Jailer
Guich Koock character TV Pitchman
Jack Pauleson character Boy in Canoe
Eric Henshaw character Father in Canoe
Robert Vinson character Soldier
Virginia Dunnam character Girl
Diamond Farnsworth character Water-skier (as Hill Farnsworth)
Bruce Paul Barbour character Man in Boat (as Bruce Barbour)
Robyn Ray character Screaming Woman
Mike Sullivan character Dam Guard
Jack Cardwell character Brandy
Sally Bondi character Swimming Deb (uncredited)
Eric Braeden character Dr. Robert Hoak (swimming double) (uncredited)
Joe Dante character Scuba Diver #2 (uncredited)
Amy Holden Jones character Hertz Clerk (uncredited)
Andrew G. La Marca character Scuba Diver #1 (uncredited)
John Sayles character Army Sentry
Phil Tippett character Scuba Diver
