The near-sighted, and obviously rich, Mr. MaGoo and his nephew, Waldo, set sail on their well-rigged boat to catch Mighty Moe, the elusive giant marlin. Walso falls overboard and Magoo rescues a seal by mistake. Thinking he is giving brandy to Waldo, Magoo serves the seal with cod-liver oil, making the seal very happy. MaGoon ties the cod-liver oil to the anchor, sinks it and promptly catches Mighty Moe. He then sails for port with his prize catch, leaving Waldo, at sea, hanging onto a buoy.