Whitney feels fear as he and Rainsford pass the island at the beginning of the story. Part of the reason he feels this fear is because he knows what experienced sailors say about it. He believes that these sailors have a sixth sense about danger. This is very different than Rainsford, who does not know anything about the island and dismisses all legends as superstitious. Here is what Whitney says:
"The old charts call it `Ship-Trap Island,"' Whitney replied." A suggestive name, isn't it? Sailors have a curious dread of the place. I don't know why. Some superstition--"
As they get closer to the island, Whitney's fear only increases. He says to Rainsford that he felt a child down his spine. The place exudes terror. Here are the words of Whitney and Rainsford:
"There was no breeze. The sea was as flat as a plate-glass window. We were drawing near the island then. What I felt was a--a mental chill; a sort of sudden dread."
"Pure imagination," said Rainsford.
"One superstitious sailor can taint the whole ship's company with his fear."
As we can see, Rainsford dismisses the fear, Whitney feels it. In this case, Whitey is correct, because it is the island where Zaroff lives. More importantly, this is the place where Zaroff hunts humans.