The Nigger of the "Narcissus" (Norton Critical Editions Series) Book

Obviously the title alone puts it somewhat beyond the pale for a high school curriculum - even the reader with a broader experience of the evolution of racial attitudes is going to approach in hopes of a more progressive stance than s/he's likely to get.
The title character is a West Indian (St. Kitts, I think) with an aristocratic demeanor and a resonant voice (one can imagine James Earl Jones in the part) who can mete out twice the disdain he receives, a sailor hired on in India for a trip back to England who immediately declares himself too ill to work. Although suggestions that he's malingering arise and at one point he sneers that he is in fact defrauding the chiefs, it turns out he is actually dying and ultimately deluding himself. All the other hands revolve around him as a sort of all-purpose "other"; the most iconic characters are the captain who embodies noblesse oblige, a Cockney left-wing agitator who we are persuaded to disdain, even though he gives voice to the reform movement of the latter 19th c. against the dreadful treatment of the merchant marine (that Conrad himself belatedly came around to, outgrowing the more "macho" libertarian attitude to seagoing culture of his earlier days) and the old salt, the 60-ish lifetime sailor who is as unquestioning of the class hierarchy of the ship as the captain.

The complex racial, social and political questions that Conrad raises despite the neutral authorial stance, the trope of the ship as a microcosm of society with a purity of purpose that is contrasted to the unexamined lives on the shore, and the sometimes breathtaking prose are all worth the work of reading it.
The other accomplishment of the book is what we would now call the "cinematic" descriptions of storms at sea - I found them dizzying and at times preferable to skim. Conrad was apparently influenced by the battle scenes in The Red Badge of Courage which I immediately picked up for comparison.