Mr. Grimes / Voice of Killer Shark
James Mason
Mr. Masterman / Voice of Eel
Bernard Cribbins
Mrs. Doasyouwouldbedoneby / Old Crone / Mrs. Tripp / Woman in Black / Water Babies 'Gate Keeper'
Billie Whitelaw
Tom
Tommy Pender
Elly
Samantha Gates
Lady Harriet
Joan Greenwood
Sir John / Voice of Polar Bear
David Tomlinson
Salmon
Jon Pertwee
(voice)
David Jason
Una Stubbs
Director
Lionel Jeffries
Writer
Michael Robson
Book
Charles Kingsley
Producer
Peter Shaw
Editor
Peter Weatherley
Director of Photography
Edward Scaife