People living at a seashore town are frightened by reports of an unknown creature called "the sea devil". Nobody knows what it is, but it's really the son of doctor Salvator. The doctor performed surgery on his son and now young Ichtiander can live under water. This gives him certain advantages, but also creates a lot of problems.
| Actor | Role |
|---|---|
 Vladimir KorenevIkhtiandr | Ikhtiandr |
 Anastasiya VertinskayaGutiere | Gutiere |
 Mikhail KozakovZurita | Zurita |
 Nikolai SimonovSalvator | Salvator |
 Anatoliy SmiraninBaltazar | Baltazar |
 Vladlen DavydovOlsen | Olsen |
| AAlbert AntonyanNot listed | Not listed |
| NNina BolshakovaNot listed | Not listed |
 Aleksandr ZakharovNot listed | Not listed |
| AAnatoliy IvanovNot listed | Not listed |
 Vladimir KudryashovNot listed | Not listed |
| NNikolay KuzminNot listed | Not listed |
 Mikhail MedvedevNot listed | Not listed |
 Yuri MedvedevNot listed | Not listed |
| AAnna NikritinaNot listed | Not listed |
| IIrina OrlikNot listed | Not listed |
 Georgi TusuzovNot listed | Not listed |
| AA. ShaginyanNot listed | Not listed |
 Sergey Boyarskiy(uncredited) | (uncredited) |
| RRafik Gasanov(uncredited) | (uncredited) |
| RRoman Isakov(uncredited) | (uncredited) |
 Ignat Leyrer(uncredited) | (uncredited) |
| BBronislav Moreno(uncredited) | (uncredited) |
 Tito Romalio(uncredited) | (uncredited) |
 Anatoli Stolbov(uncredited) | (uncredited) |
 Stanislav Chekan(uncredited) | (uncredited) |