While on Christmas vacation, ten-year-old Davey Reid and his parents hire a fishing guide, Lewis Bradon, to take them on a boat into the Gulf of Mexico, where Davey's father hopes to catch the first tarpon of the year. Davey enjoys the warm sun, the bright water, and the interesting animals, all of which make him forget about his dreary boarding school back home. He tries to tell his parents about the porpoises that he sees near the boat, but they are dismissive of him. His father worries with getting the fishing rods prepared while his mother reads a book. Only Lewis pays any attention to the boy. He lets Davey drive the boat for a little while. For lunch, they stop on an island beach. Davey wants to go explore, but his parents insist that he stay within their sight and that he doesn't go swimming alone. He wanders down the beach, finding shells, fiddler crabs, and coconuts, and he climbs on mangrove trees. He feels connected to the vivacity of the environment around him. Meanwhile, back near the boat, Davey's parents get into a little argument. Mr. Reid is upset that his son isn't more like he was when he was a boy: strong and brave. But his wife worries about Davey's safety. They eventually settle into silence while Lewis finishes preparing their lunch. Davey comes back to his parents and goes swimming. He tries to float like his father does, but he fails and his father laughs at him. Their lunch is cut short when Mr. Reid sees another boat on the water, which he believes belongs to the Emerys, a couple that has held the record for catching the first tarpon of the year for a decade. Mr. Reid rushes his family aboard the boat and has Lewis set sail. After showing Davey and his mother how to use the reels, the three of them start fishing. They follow the Emerys' boat, believing that they know where the fish are. After some time, they see many tarpon rolling, but Lewis says that they won't bite yet. They stay out all afternoon. Mrs. Reid is the only one to catch anything, but it's not a tarpon. She asks her husband if they can go in yet, but he wants to stay out as long as the Emerys. After some pleading, he agrees that they'll leave in an hour. As they're talking, Davey gets a bite on his line. Lewis says that he's got a tarpon. Mr. Reid coaches his son on how to reel in the fish. When his wife tries to help her son hold the reel, he swats her hand away. After a long battle, the fish gets tired and they catch it. Davey is impressed by its size, as it's one pound heavier than he is. His father says that he is very proud of his boy. When they get back to the dock, Davey is congratulated by many people. They hang up the fish and Mr. Reid wants Davey to smile for a picture, but Davey, seeing that the fish has died, struggles to smile. Lewis tells him that the fish went to fish heaven, but Davey is still upset. He starts crying at dinner, and Mrs. Reid takes him up to bed, thinking he's exhausted after a long day without a nap. In bed, Davey has trouble sleeping. He thinks about the fish. He imagines it in heaven, but it is still belly-up. But then, the fish slowly rights itself in his mind and begins to happily swim through heaven.