The nudity in this film is limited to immediately after Karik (Aleksei Chertsov, 9) and Valya (Anna Dikul, 7) shrink in size. They fall into the water, and we see their nude back-sides as they fall. Afterward they wear loincloths.
There is a skinny dipping scene at beginning of film where one boy has rear nudity. There is also frontal and rear nudity of two boys and a girl diving or jumping into river.