Narrative started life as a serialized novel, switched early on to pretending to be a true story (hence the 'Narrative' part of the title, which in the 1830's connoted a true story), and concluded with a fictional argument between Poe and Pym about the authenticity of the narrative. But while academics love the text's quirkiness, it's the horror that has captivated several generations of readers.
We first follow Pym on one short sailing disaster caused by a drunk friend at the helm. Then Pym stows away on that friend's father's cargo ship for adventure. And he really gets some crazy-ass adventure.
Poe's genius in the first two-thirds of the novel lies in his willingness to move from one carefully though sometimes purple-prose-depicted horror to the next, with little or no pause. Fear of drowning, fear of cannibalism, fear of being buried alive, fear of being attacked by an animal, fear of starving or dying from lack of water... Poe hits them all. Do terrible smells make you vomitous? They're here too. And terrible flavours in your mouth. And drunkenness that actually imperils your life. And sharks. And festering wounds. And painful, debilitating gastric distress caused by eating too many filberts.
Later writers, most notably H.P. Lovecraft, would learn from Poe to hit the reader with uncomfortable environmental details as quickly as possible, and repeatedly -- cold, wet, smells, claustrophobia, and so many others. Show the reader the terror of the environment, not just the terror of the circumstances.
Two-thirds of the way through the novel, Poe and his pocket Hercules companion Dirk Peters (!), a part-Native American who keeps saving our hero once they meet up, finally get rescued. So begins the final stretch of the novel that has been more influential than any other: the journey to the Southern polar regions. There, Pym, Peters, and the crew of the Jane Guy encounter an undiscovered tribe on an island called Tsalal, various environmental mysteries, and finally the mysteries of the pole itself.
It seems, per some speculation at the time, that the oceans empty in massive cataracts into some colossal abyss at the South Pole. And there, abruptly, the story ends. Pym and Peters make it home, we're told (indeed, we've known this from the beginning of the tale). But the final mysterious and haunting images are never explained or expanded upon. It's those images, however, and some of the events on the island of Tsalal, that fascinated Jules Verne and H.P. Lovecraft enough (to name just two) to write their own Pym-referencing tales of the South Pole.
The whole thing is dense but fast-moving -- the horrors race by. And Poe's interest in inversions and subversions make the later sections a fascinating study. Characters (Dirk Peters the "half-breed"), ships (the Jane Guy is a hermaphrodite, an actual type of ship melding two different and distinct ship designs), and even the weird water of Tsalal combine disparate characteristics. Whiteness becomes sinister, especially in the strange, frothing, white waste seas as one leaves Tsalal and moves farther South. There are strange white creatures with red teeth. There are giant humanoid figures looming out of the mist. There is a South Pole that is warmer than it should be.
It's a shame Poe never saw his way to truly finishing the novel. However, it's possible that the unanswered mysteries of the final pages have helped keep the work alive in the imaginations of both readers and the writers who have been inspired to follow in its path. The Narrative of Arthur Gordon Pym of Nantucket achieves disparate moments of visceral horror and existential, cosmic mystery. Highly recommended.