Though Huck does not intentionally hide the truth from readers, he is still an unreliable narrator in his own way. This is mostly due to specific limiting factors in his life: first, he is 13 years old and has not gone through regular schooling. This leads to several incorrect references and allusions, like in the following conversation he has with Jim:
“Well, Henry he takes a notion he wants to get up some trouble with this country. How does he go at it—give notice?—give the country a show? No. All of a sudden he heaves all the tea in Boston Harbor overboard, and whacks out a declaration of independence, and dares them to come on. That was his style—he never give anybody a chance. He had suspicions of his father, the Duke of Wellington.”
Here, Huck is mixing up the unrelated histories of Henry VIII, the Boston Tea Party, the Declaration of Independence, and the Duke of Wellington.
Huck is also unreliable because he has been raised as a white child in a racist society. This makes it so that the things he believes about Jim and other Black people are deeply limited and incorrect. For example, Huck is surprised when he witnesses the depth of Jim’s intellect as well as his emotional range. When Huck witnesses Jim mourning the fact that he has been separated from his family, he is surprise to find that Jim “cared just as much for his people as white folks does for their’n.” That he doesn’t already know this to be true makes Huck an unreliable narrator, while, at the same time, allowing readers to watch Huck mature into someone who no longer stereotypes and judges Black people in the same way.