The Fellows From the Kanonersky Island (1960)

Two friends, Valya and Slava, come up with an interesting game for the kids in their neighborhood—called "sea crew"—and an old abandoned shed serves as their "ship." But the game is just a game, and the kids want to participate in something real. Then they receive a letter from an older friend — the virgin lands where he is heroically working are short of tractors. Here it is, a real job — they need to collect scrap metal to build a tractor! What's more, the kids decide to raise a sunken barge from the bottom of the Neva River...