Nymphette's of the Wild Sex(1983)

Original title: Ninfetas do Sexo Selvagem

Young family on a yacht floating on the waves of the tropical seas, moored to some islets which seemed initially, and while their two daughters playing on the beach, unreasonable parents managed to blow up the boat with him. Children left alone on the island, they managed to survive, and now they have grown up, and the island was not so uninhabited...