Gulliver stays home for five months, but he then leaves his pregnant wife to set sail again, this time as the captain of a ship called the Adventure. Many of his sailors die of illness, so he recruits more along the way. His crewmembers mutiny under the influence of these new sailors and become pirates. Gulliver is left on an unknown shore, after being confined to his cabin for several days. In the distance, he sees animals with long hair, goatlike beards, and sharp claws, which they use to climb trees. Gulliver decides that these animals are extremely ugly and sets forth to find settlers, but he encounters one of the animals on his way.
Gulliver takes out his sword and hits the animal with the flat side of it. The animal roars loudly, and a herd of others like it attack Gulliver by attempting to defecate on him. He hides, but then he sees them hurrying away. He emerges from his hiding place to see that the beasts have been scared away by a horse. The horse observes Gulliver carefully, and then it neighs in a complicated cadence. Another horse joins the first and the two seem to be involved in a discussion. Gulliver tries to leave, but one of the horses calls him back.
The horses appear to be so intelligent that Gulliver concludes that they are magicians who have transformed themselves into horses. He addresses them directly and asks to be taken to a house or village. The horses use the words “Yahoo” and “Houyhnhnm,” which Gulliver tries to pronounce.
Gulliver is led to a house, and he takes out gifts, expecting to meet people. He finds instead that there are more horses in the house, sitting down and engaged in various activities. He thinks that the house belongs to a person of great importance, and he wonders why they should have horses for servants. A horse looks Gulliver over and says the word “Yahoo.” Gulliver is led out to the courtyard, where a few of the ugly creatures Gulliver has seen are tied up. Gulliver is lined up and compared with one of the creatures, and Gulliver finds that the creature does look quite human. The horses test Gulliver by offering him various foods: hay, which he refuses, and flesh, which he finds repulsive but which the Yahoo devours. The horses determine that he likes milk and give him large amounts of it to drink.
Another horse comes to dine, and they all take great pleasure in teaching Gulliver to pronounce words in their language. They cannot determine what he might like to eat until Gulliver suggests that he could make bread from their oats. He is given a place to sleep with straw for the time being.
Gulliver endeavors to learn the horses’ language, and they are impressed by his intellect and curiosity. After three months, he can answer most of their questions and tries to explain that he comes from across the sea, but the horses, or Houyhnhnms, do not believe that such a thing is possible. They think that Gulliver is some kind of Yahoo, though superior to the rest of his species. He asks them to stop using that word to refer to him, and they consent.