Lemuel Gulliver tells the story "A Voyage to the Country of the Houyhnhnms." Captain Gulliver makes note in "A Letter" that he has done so at the urging of his cousin Sympson.
His trip to the Land of the Houyhnhnms is his final journey and his favorite of all the fantastical places he visited. The tale takes place in the fourth part of the novel, Gulliver's Travels by Johnathan Swift.
Originally, Gulliver set out again to support his growing family, but this time as the captain of his own ship, after taking an "advantageous offer to be a captain of adventure" (4.1) The men on Gulliver's ship do not particularly admire his style of leadership and confine him to his cabin; eventually Gulliver is marooned on a mysterious land, where he encounters the race of Houyhnhnms.