Bo Jakobsen as Benny (voice)

Jesper Klein as Tadpole (voice)

Peter Belli as Octopus (voice)

Jytte Abildstrøm as Dagny (voice)

Otto Brandenburg as Lobster Boy (voice)

Jytte Hauch-Fausbøll as Benny's Mother (voice)

Rolf Krogh as Ornithologist (voice)

Povl Dissing as First Pirate (voice)

Per Bentzon Goldschmidt as Second Pirate (voice)

Per Tønnes Nielsen as Cowboy (voice)

Aya as Mermaid (voice)

Maia Årskov as Mermaid (voice)

Trille as Mermaid (voice)

Christian Sievert as Crab (voice)

Allan Botschinsky as Seahorse (voice)