The father and Fritz take this day to return to the shipwreck to salvage materials. They must also bring back the livestock. Before leaving the island, the father erects a pole and places a makeshift flag. If there is trouble, Elizabeth is to lower the flag and shoot the rifle he leaves her three times so they know to return. Otherwise, the two men will stay on board overnight, giving them ample time to load the barrel-raft they have constructed for transporting themselves and the goods. As they are about to leave, Fritz suggests that they rig a sail to catch the steady breeze and save them the trouble of rowing against ocean currents.

On board, the men busy themselves searching for valuable merchandise. They find a large quantity of powder and shot for their rifles, as well as more guns, swords, daggers, and knives. They believe they can never have enough weapons against wild animals and possibly pirates or other marauders from the sea. They also pack kitchen utensils, wine from the captain's cabin, and meats, soups, seeds, and grains from the storage compartments. In addition, they load their kegs with more tools, sulphur for matches, and agricultural implements. By the time they finish, their raft sits very low in the water.

Nightfall darkens the landscape, but they see by the light of the campfire on shore that the flag is still flying high. They know the family is safe. This fact plus the work they have done provide them with sound sleep.

In the morning, Fritz and his father make floating belts to wrap around the livestock to help them swim. They will tie the animals together and gently pull them alongside the raft. Although the pig is stubborn, eventually they successfully launch the cow, goats, and sheep. On their raft, the father and Fritz relax, munching on crackers. The trip back goes smoothly until the father, looking through a "glass" at the distant shore, hears a loud cry from Fritz.

The father sees Fritz with a rifle at his shoulder, prepared to shoot. In the water is a huge shark threatening to eat one of the sheep. As the shark turns to make a fatal attack, Fritz shoots and wounds him. A trail of blood moves through the water as the shark swims away.