Part I: A Voyage to Lilliput
- 4 May 1699 – 13 April 1702
The travel begins with a short preamble in which Lemuel Gulliver gives a brief outline of his life and history before his voyages.
During his first voyage, Gulliver is washed ashore after a shipwreck and finds himself a prisoner of a race of tiny people, less than 6 inches (15 cm) tall, who are inhabitants of the island country of Lilliput. After giving assurances of his good behaviour, he is given a residence in Lilliput and becomes a favourite of the Lilliput Royal Court. He is also given permission by the King of Lilliput to go around the city on condition that he must not hurt their subjects.
At first, the Lilliputians are hospitable to Gulliver, but they are also wary of the threat that his size poses to them. The Lilliputians reveal themselves to be a people who put great emphasis on trivial matters. For example, which end of an egg a person cracks becomes the basis of a deep political rift within that nation. They are a people who revel in displays of authority and performances of power. Gulliver assists the Lilliputians to subdue their neighbours the Blefuscudians by stealing their fleet. However, he refuses to reduce the island nation of Blefuscu to a province of Lilliput, displeasing the King and the royal court.
Gulliver is charged with treason for, among other crimes, urinating in the capital though he was putting out a fire. He is convicted and sentenced to be blinded. With the assistance of a kind friend, "a considerable person at court", he escapes to Blefuscu. Here, he spots and retrieves an abandoned boat and sails out to be rescued by a passing ship, which safely takes him back home.
Part II: A Voyage to Brobdingnag
- 20 June 1702 – 3 June 1706
Gulliver soon sets out again. When the sailing ship Adventure is blown off course by storms and forced to sail for land in search of fresh water, Gulliver is abandoned by his companions and left on a peninsula on the western coast of the North American continent.
The grass of Brobdingnag is as tall as a tree. He is then found by a farmer who is about 72 ft (22 m) tall, judging from Gulliver estimating the man's step being 10 yards (9 m). The giant farmer brings Gulliver home, and the his daughter Glumdalclitch cares for Gulliver. The farmer treats him as a curiosity and exhibits him for money. After a while the constant display makes Gulliver sick, and the farmer sells him to the Queen of the realm. Glumdalclitch (who accompanied her father while exhibiting Gulliver) is taken into the Queen's service to take care of the tiny man. Since Gulliver is too small to use their huge chairs, beds, knives and forks, the Queen commissions a small house to be built for him so that he can be carried around in it; this is referred to as his "travelling box".
Between small adventures such as fighting giant wasps and being carried to the roof by a monkey, he discusses the state of Europe with the King of Brobdingnag. The King is not happy with Gulliver's accounts of Europe, especially upon learning of the use of guns and cannons. On a trip to the seaside, his traveling box is seized by a giant eagle which drops Gulliver and his box into the sea where he is picked up by sailors who return him to England.
Part III: A Voyage to Laputa, Balnibarbi, Luggnagg, Glubbdubdrib and Japan
- 5 August 1706 – 16 April 1710
Setting out again, Gulliver's ship is attacked by pirates, and he is marooned close to a desolate rocky island near India. He is rescued by the flying island of Laputa, a kingdom devoted to the arts of music, mathematics, and astronomy but unable to use them for practical ends. Rather than use armies, Laputa has a custom of throwing rocks down at rebellious cities on the ground.
Gulliver tours Balnibarbi, the kingdom ruled from Laputa, as the guest of a low-ranking courtier and sees the ruin brought about by the blind pursuit of science without practical results, in a satire on bureaucracy and on the Royal Society and its experiments. At the Grand Academy of Lagado in Balnibarbi, great resources and manpower are employed on researching preposterous schemes such as extracting sunbeams from cucumbers, softening marble for use in pillows, learning how to mix paint by smell, and uncovering political conspiracies by examining the excrement of suspicious persons (see muckraking). Gulliver is then taken to Maldonada, the main port of Balnibarbi, to await a trader who can take him on to Japan.
While waiting for a passage, Gulliver takes a short side-trip to the island of Glubbdubdrib which is southwest of Balnibarbi. On Glubbdubdrib, he visits a magician's dwelling and discusses history with the ghosts of historical figures, the most obvious restatement of the "ancients versus moderns" theme in the book. The ghosts consist of Julius Caesar, Brutus, Homer, Aristotle, René Descartes, and Pierre Gassendi.
On the island of Luggnagg, he encounters the struldbrugs, people who are immortal. They do not have the gift of eternal youth, but suffer the infirmities of old age and are considered legally dead at the age of eighty.
After reaching Japan, Gulliver asks the Emperor "to excuse my performing the ceremony imposed upon my countrymen of trampling upon the crucifix", which the Emperor does. Gulliver returns home, determined to stay there for the rest of his days.
Part IV: A Voyage to the Land of the Houyhnhnms
- 7 September 1710 – 5 December 1715
Despite his earlier intention of remaining at home, Gulliver returns to sea as the captain of a merchantman, as he is bored with his employment as a surgeon. On this voyage, he is forced to find new additions to his crew who, he believes, have turned against him. His crew then commits mutiny. After keeping him contained for some time, they resolve to leave him on the first piece of land they come across, and continue as pirates. He is abandoned in a landing boat and comes upon a race of deformed savage humanoid creatures to which he conceives a violent antipathy. Shortly afterwards, he meets the Houyhnhnms, a race of talking horses. They are the rulers while the deformed creatures that resemble human beings are called Yahoos.
Gulliver becomes a member of a horse's household and comes to both admire and emulate the Houyhnhnms and their way of life, rejecting his fellow humans as merely Yahoos endowed with some semblance of reason which they only use to exacerbate and add to the vices Nature gave them. However, an Assembly of the Houyhnhnms rules that Gulliver, a Yahoo with some semblance of reason, is a danger to their civilization and commands him to swim back to the land that he came from. Gulliver's "Master," the Houyhnhnm who took him into his household, buys him time to create a canoe to make his departure easier. After another disastrous voyage, he is rescued against his will by a Portuguese ship. He is disgusted to see that Captain Pedro de Mendez, whom he considers a Yahoo, is a wise, courteous, and generous person.
He returns to his home in England, but is unable to reconcile himself to living among "Yahoos" and becomes a recluse, remaining in his house, avoiding his family and his wife, and spending several hours a day speaking with the horses in his stables.