The film opens with Donald Duck taking his nephews, Huey, Dewey, and Louie, to sea. They are first seen rowing out to Donald's large ship in a small rowboat, with Donald conducting the rowing. Aboard Donald's ship, he acts as a proud and able sea captain. He is forced to move aside when a seagull almost defecates on his sea captain hat, and then discovers that his nephews have fallen asleep. He yells at them to wake up and they bump into each other in their haste to follow his orders. They are asked to raise the anchor, but as they are raising it, it gets caught on a rock under the water. Not realizing what's wrong, Donald attempts to raise the anchor himself but runs into the same problem. Angrily, he tries again but pushes so hard the boat sinks instead of the anchor rising and goes underwater. At first, Donald does not know what has happened – even thinking he sees "flying fish" and "flying turtles" – but finally finds out what has happened, and lowers the anchor to make the boat rise. In the process, he is thrown into the mast, getting tangled up in flags. His nephews find this funny and laugh, but Donald responds by angrily telling them to raise the sail. However, they do not raise it properly, pulling the sail, while still between its masts, upward instead of outward. When he tells them to do it the right way, they say "Aye aye, sir!" and unintentionally let it fall on Donald. Donald loses his temper and raises the sail himself, and the ship finally leaves the dock. However, Donald forgets to untie the rope holding the ship to the dock, and the ship stays in place. Then a gust of wind tears the mast loose, taking Donald up with it and knocking his hat off. He tells his nephews to lower him down so he can retrieve it. But suddenly, a big, hungry shark appears, wanting to devour Donald. His nephews mess up again by lowering the rope downwards instead of upwards and saying "Aye aye, sir!", letting go of the rope and letting him fall on the rope toward the shark's mouth. He gets off just in time and escapes by hanging on a cable attached to the boat. His nephews set out to rescue him by getting into the rowboat and paddling to below the spot where he is hanging, carrying a life raft. However, the shark scares them off after Donald has already let go, causing him to fall down into the water right in front of the shark. A fast chase around the bay then ensues, as Donald attempts to avoid getting eaten by the shark. Several close calls happen, including one where Donald is in the shark's mouth and is saved only by his life raft preventing the shark's jaws from closing. Finally, Donald is rammed into his ship, with his hat being messed up in the process. Enraged, he charges full speed at the shark and punches it in the nose, knocking it backwards onto a buoy. The film then ends with Donald and his nephews rowing back to shore with the life raft on Donald's rear end.
