Bradford Dillman
Paul Grogan
                                    Heather Menzies
Maggie McKeown
                                    Kevin McCarthy
Dr. Robert Hoak
                                    Keenan Wynn
Jack
                                    Dick Miller
Buck Gardner
                                    Barbara Steele
Dr. Mengers
                                    Belinda Balaski
Betsy
                                    Melody Thomas Scott
Laura Dickinson
                                    Bruce Gordon
Colonel Waxman
                                    Barry Brown
Trooper
                                    Paul Bartel
Mr. Dumont
Shannon Collins
Suzie Grogan
Shawn Nelson
Whitney
                                    Richard Deacon
Earl Lyon
Janie Squire
Barbara Randolph
Roger Richman
David
Bill Smillie
Jailer
                                    Guich Koock
TV Pitchman
Jack Pauleson
Boy in Canoe
Eric Henshaw
Father in Canoe
Robert Vinson
Soldier
Virginia Dunnam
Girl
Diamond Farnsworth
Water-skier
                                    Bruce Paul Barbour
Man in Boat
Robyn Ray
Screaming Woman
Mike Sullivan
Dam Guard
Jack Cardwell
Brandy
Sally Bondi
Swimming Deb (uncredited)
                                    Eric Braeden
Dr. Robert Hoak (swimming double) (uncredited)
                                    Joe Dante
Scuba Diver #2 (uncredited)
                                    Amy Holden Jones
Hertz Clerk (uncredited)
Andrew G. La Marca
Scuba Diver #1 (uncredited)
                                    John Sayles
Army Sentry (uncredited)
                                    Phil Tippett
Scuba Diver (uncredited)
Piranhas
Released
$ 660,000
$ 16,000,000