When he was sixteen years old, Robin Lee Graham decided to sail around the world by himself. In the summer of 1965, Graham set sail from his home port of Los Angeles in his 24-foot fiberglass sloop named Dove. He was accompanied only by his two cats, Joliette and Susette. During his trip, Graham kept an audio diary, and he often recorded his feelings of loneliness during calm weather and anxiety when he faced squalls and other dangerous weather situations. He successfully sailed across the Pacific Ocean, and he visited many Pacific islands, including the Solomon Islands, American Samoa, and the Yasawa Islands. During his journey, Robin Lee Graham met fellow world traveler Patti Ratterree, and the two wed in Australia. They traveled together on Dove across most of the Indian Ocean. After returning to Los Angeles almost five years after he set sail, Graham co-wrote a book named Dove. The story of his journey was also made into a movie of the same name.Which sentence best expresses the central idea of the passage?