Prendick finds himself in the completely alien world of the Pacific (alien to him at least). The ocean serves as transportation to Moreau's island, almost like a certain wardrobe from a certain fantasy novel.
Everything about his new surroundings confounds Prendick and his worldview. He can't understand why Captain Davis treats people as he does. He doesn't understand what it is about Moreau's men that give him "a spasm of disgust" (6.4). Even Montgomery and Moreau, two men he shares much in common with from occupation to nationality, are utterly foreign to him. Between Moreau's secrecy and Montgomery's secret past, everything about everything seems to be, well, weird.
Prendick is a scientist at heart, so he almost can't help but delve into the mysteries of Moreau's island. He wonders what Moreau is up to, and why his helpers are physically disfigured. He also can't understand what Moreau is doing all the way out in the Pacific. Why didn't he just stay in England? After all, what's wrong with a little vivisection? You've heard the old saying about curiosity and its effects on cats, right?
Once Prendick believes he's next on Moreau's chopping block, the initial fascination ends fast. As he learns more and more about the Beast Folk, he begins to loath what Moreau has done on the island. Worse, Prendick sees the torture the poor Beast Folk have to endure and sympathizes with them.
Still, he is also repulsed by how they look and how they represent the utter disregard for nature as he knows it. After witnessing the fate of the Leopard Man, Prendick claims to have "lost faith in the sanity of the world when [he] saw it suffering the painful disorder of the island" (16.92). Yeah, we'd qualify that sentiment as frustrating.
Moreau dies, and the nightmare begins. Prendick is left alone on the island as Montgomery dies and then even his companion, Dog Man, dies. The Beast Folk begin to revert back to their animal selves, and the whole island becomes a beastman-eat-dog kind of situation. It's survival of the fittest, the ultimate evolutionary test.
Prendick returns to the very ocean that almost claimed his life in the first place. There's a certain poetry to the whole situation, isn't there? The very ocean that brought him to the strange world Moreau created is the only route by which he can leave it behind. And so Prendick is picked up by another ship and brought back to England.
Unfortunately, Prendick has been scarred by his time on Moreau's island. Now every Londoner he bumps into reminds him of one of Moreau's beastly creations. Not finding solace in the hustle and bustle of ye old London town, Prendick moves to the country and takes up astronomy. Unable to find peace in this world, he looks beyond it, perhaps initiating another voyage—but an inner journey this time, the kind where you get to stay home for it.