James Mason

Mr. Grimes / Voice of Killer Shark

Bernard Cribbins

Mr. Masterman / Voice of Eel

Billie Whitelaw

Mrs. Doasyouwouldbedoneby / Old Crone / Mrs. Tripp / Woman in Black / Water Babies 'Gate Keeper'

Tommy Pender

Tom

Samantha Gates

Elly

Joan Greenwood

Lady Harriet

David Tomlinson

Sir John / Voice of Polar Bear

Jon Pertwee

Salmon

David Jason

(voice)

Una Stubbs

(voice)

Lionel Jeffries