The books in the series:
- Dolphin Boy (1967)
- Daughters of the Dolphin (1968)
- Destiny and the Dolphins (1969)
The Dolphin Trilogy contains examples of:
- Abandoned Area: In Dolphin Boy, John explores Crab Island, the now-Deserted Island where he spent his infancy, and the ruins of his dead parents' house and laboratory.
- Affluent Ascetic: After John comes into his parents' fortune, he builds a house and servants' quarters on Crab Island so he can use it as a home base, and pays scientists in Scotland to continue his parents' research. But although he pays his servants a high salary and spends lots of money on scientific equipment, he continues to spend most of his time in the ocean, living off raw seafood and hardly spending anything on himself.
- The Ageless: In the series, sea life doesn't age, so after John reaches adulthood, he watches the humans he knows grow older while he stays the same age. In Daughters of the Dolphin, he meets a dolphin who's millennia old.
- Alone Among the Couples: As an adolescent, John starts to feel lonely because all the dolphins are finding mates, but he has no one of his own species.
- Attempted Rape: In Destiny and the Dolphins, Lord James Renshaw invites Vinca onto his boat and takes her miles out to sea so she won't be able to escape when he forces himself on her. She escapes by jumping overboard. When she doesn't reappear, James, thinking he's killed her, returns to London to confess what happened, only to learn that Vinca simply swam to shore.
- Cry into Chest: Vinca cries into John's shoulder as she tells him about James' assault on her.
- Direct Line to the Author: Dolphin Boy presents itself as the work of Mark Ryall, a doctor who examined John when he was an infant and gathered as much information as he could find about his later life.
- Double Consciousness: As an adult, John doesn't feel entirely at home either on land or at sea. Human social norms baffle him, and humans can be deliberately cruel in a way that dolphins never are. But when he's with dolphins, he longs for the intellectual stimulation of talking to his own kind and reading human books.
- Exactly What It Says on the Tin: John's father, Sir Arthur Averill, owned an electronic equipment firm called Electronic Equipment Ltd.
- Foul First Drink: When John is reunited with Della in Montego Bay, Della's father Rupert, who wants her to marry Mark Watson, puts John in as many social situations as possible so he'll make embarrassing gaffes in front of Della. At one point he serves John a very dry wine, which John spits onto the tablecloth in front of all the guests.
- Frozen Face: Throughout his early life, John has no facial expressions and is Unable to Cry or laugh because there were no humans he could learn those behaviors from. It isn't until he meets Della that he begins to emote in a more typical manner, although he still looks almost expressionless compared to most people.
- Hair-Contrast Duo: Daughters of the Dolphin introduces the Phelan twins, outgoing dark-haired Vinca and introverted blonde Syn.
- Heroic Dolphin: In Destiny and the Dolphins, John, Vinca, and Syn have been captured by diamond thieves who plan to torture John, rape Vinca and Syn, and then kill all three of them as revenge for the fight they put up earlier. But as the thieves are dragging them through the water to shore, the three send out a distress call. Within minutes, dozens of dolphins have arrived to kill the criminals.
- Inescapable Net: How John is reintroduced to society in Dolphin Boy. He deals with his sorrow over Della's disappearance by swimming at maximum speed, right into the trawl of the research vessel Poseidon. The people aboard notice him thrashing about and think he's a large fish, until they pull the net out of the water and are astonished to find a man trapped inside.
- Innocent Fanservice Guy: John has no nudity taboo, and even after he's taught to wear clothes he prefers to go without. When Della wakes up on Crab Island after her near-drowning, she finds that her rescuer is a handsome, muscular naked man who reminds her of a Greek god.
- Left Hanging: In Destiny and the Dolphins, John, Vinca, and Syn decide to tell the dolphins to let them know of any sign of human life. John thinks that, although it isn't safe for any of them to leave the island, they'll eventually have to find out what happened to the rest of the world. However, we never learn if anyone survived the plague, because the trilogy ends there. Both Vinca and Syn also seem to be about to start a relationship with John, but the book ends before anything can happen.
- The Nicknamer: Dolphins don't have names, but John's human instincts lead him to associate each dolphin with a string of sounds. In human speech, his adoptive mother would be called Mala, and his best friend would be Tron.
- Not What It Looks Like: In Dolphin Boy, Della accepts John's marriage proposal, and goes to tell Mark Watson about her choice. John sees Della embracing Mark and kissing him goodbye and thinks she's abandoned him. He flees into the ocean before she can catch up with him and explain.
- Over-the-Shoulder Carry: In Daughter of the Dolphins, men kidnap Syn from Crab Island so they can hold her for ransom. One of them carries her over his shoulder back to their boat.
- Parrot Pet Position: In Dolphin Boy, John tames a small octopus by feeding it bits of lobster. The octopus can't swim fast enough to keep up with him, so it rides on his shoulder with a tentacle wrapped around his neck.
- The Plague: In Destiny and the Dolphins, genetically modified strains of typhoid fever and bubonic plague are released into the population. These illnesses have a fatality rate of nearly 100%, and despite the efforts of most countries to close their borders, they spread all over the world. Eventually radio broadcasts from each country fall silent, leaving John, Vinca, and Syn alone on Crab Island.
- Power Fist: In Dolphin Boy, Oswald Raynor gives John a pair of knuckledusters with sharp points, partly so he can defend himself against sharks and partly to weigh him down and help him stay below the surface more easily.
- Previously on…: Daughters of the Dolphin begins with a summary of Dolphin Boy.
- Radiation-Induced Superpowers: Early in her pregnancy, John's mother Raye is briefly exposed to nuclear radiation, giving her son more efficient lungs than other humans and glands in his skin that cause him to be covered in oil when he's in the water for a certain period of time. These adaptations allow him to survive life with the dolphins. In Daughters of the Dolphin, pregnant widow Mary Phelan helps continue Arthur's research in wirelessly transmitting power. Her twin daughters, Vinca and Synclaire, are born with the same adaptations.
- Raised by Wolves: John himself, of course, but also Vinca and Syn. After their mother dies, John is made their legal guardian. After he teaches them to hold their breaths in the water, he gives them each to a different female dolphin to be raised. He reasons that if they're raised in the ocean, they can later learn to walk and live on land, but if they're raised on the land, they can never learn to live in the sea.
- Rescue Romance: In Dolphin Boy, John rescues Della Lord, a young woman who has been washed overboard from a yacht, and carries her to Crab Island on his back. She is the first human woman he's ever met, and he is instantly entranced. After she teaches him basic English, the two have sex. Then John has to spend several days in the ocean to care for the dying Mala, and by the time he returns, Della is gone, leaving only a note he can't read. It takes him months to find her again.
- Sapient Cetaceans: Dolphins and whales are fully sapient and all speak Dolphinese. John tries to prove the intelligence of whales in his unsuccessful efforts to get whaling banned.
- Sense Freak: Humans can't smell underwater, so when John teaches Vinca and Syn to walk on Crab Island, they're both fascinated and delighted by all the different scents.
- Sensory Overload: The undersea world is so quiet and peaceful that when John and later Vinca and Syn enter the upperair world, they both become overwhelmed by the incessant din.
- Shoe Phone: In Destiny and the Dolphins, John has a ring that contains a transmitter and a pair of earrings that contain receivers made for both Vinca and Syn so he can talk to them when they aren't living together.
- Shrouded in Myth: As he's growing up, John is sighted several times by humans, and becomes known as the Merman of the Caribbean. Even after he rejoins society, a lot of people still believe the rumors that he's an actual merman who transforms into a human while he's out of the water.
- The Sleepless: When John, Vinca, and Syn are on land, the difficulty of fighting gravity causes them to need sleep, but while they're in the ocean, they can stay awake indefinitely. All three of them spend almost all of their childhoods awake.
- Solar-Powered Magnifying Glass: During her time on Crab Island, Della uses her watch lens to light a fire. John is willing to try the fish she cooks for him, but he greatly prefers raw fish.
- Sole Survivor: As an infant, John lives on an island in the Caribbean, where his parents are creating the prototype of their latest invention. Then the prototype explodes, killing everyone on the island except John, whose nurse had just set him down near the cliff on the back of the island, partially protecting him from the concussion wave. John is flung harmlessly into the sea, where he is rescued by a pod of dolphins.
- Speaks Fluent Animal: John learns to speak Dolphinese. He never entirely masters it because he can't hear the highest frequencies, but he becomes close to fluent.
- A Taste of the Lash: In Destiny and the Dolphins, the diamond thieves whip Syn in order to force her to talk.
- Tranquil Fury: John appears outwardly calm even when he's furious. When he confronts Syn's kidnapper in Daughters of the Dolphin, the kidnapper is creeped out by his apparent lack of emotion.
- Troubled Fetal Position: After Syn is kidnapped in Daughters of the Dolphin, she is locked in a cabin, where she curls in a ball on the bed.
- World War III: In Destiny and the Dolphins, China and India engage in increasingly violent border disputes while Russia eggs China on. Then, while China is occupied with the fighting in India, Russia invades China. The war gradually spreads across the whole world. Unlike most examples, the war never turns nuclear - it's biological warfare that wipes out humanity.
