One could reasonably argue that Ishmael in Moby Dick is something of an unreliable narrator. He is not an unreliable narrator in the same sense as a character in Poe, perhaps, but he is a character who nonetheless gives the impression that we can't take anything he says at face value.

First of all, let's look at how Ishmael introduces himself. He doesn't say “I'm Ishmael” or “My name is Ishmael”. Instead, he says “Call me Ishmael,” the implication being that perhaps Ishmael isn't his real name. Immediately, we're placed on our guard. If, as we suspect, Ishmael can't be relied on to tell us his real name, then how can we trust anything he says?

At the very least, one could argue that Ishmael's unusual introduction allows him to shape the narrative in the way that he wants. Of course, it doesn't automatically follow from this that everything Ishmael tells us is a lie. But it does mean that we need to have our wits about us.

A good example of Ishmael's unreliability as a narrator comes when he tells the tale of a mutiny on another ship. There is nothing especially unusual about this, one might think; mutinies were quite regular on ships in those days, so it's not necessarily the case that Ishmael is spinning a nautical yarn.

But then Ishmael undermines the truth of his tale somewhat by informing us that he's going to tell us the version of the story that he told to some Catalan sailors when they were having a drink together. This immediately raises the following question: how many versions are there? That Ishmael is giving us the same version he gave to a group of (possibly) drunken sailors should arouse our suspicion that this is a tall take embroidered for entertainment value, the kind of shaggy-dog story people often tell each other when they're having a drink.