I'm really late on this one. Words just weren't working for me. We'll blame it on the long ponderous days of travel in this chapter.
Sam could be a bit agoraphobic, or he could just be sensibly paranoid about floating down the river with open plains all around. I'm going with a little bit of Column A and a little bit of Column B. I think anyone sane would be "sensibly paranoid." Aragorn at the very least counts as such in his fears of the Dark Lord's machinations while the Fellowship rested with the elves.
Much of this chapter is a lull before the storm.
Boromir's resolve is clearly cracking, and his fall is hinted at with all the subtly of a boulder. We've known the he is prideful and that he holds a belief that the Ring could be turned against the Dark Lord. He's actually starting to behave in a way that reminds me of Renfield (minus consuming lives). He's twitchy, shifty, muttering to himself, and compulsively biting his nails. He's having difficulty not actively stalking Frodo, and it's only Frodo's steadfast support of Aragorn that largely keeps Boromir staying in line with Aragorn's leadership.
This chapter also addresses the elephant in the room, Gollum following the party is now acknowledged and discussed. Not only has Aragorn known of Gollum, but he has even made attempts to capture their tail. That method failing, and the secret in the open, they switch to attempts at faster travel and journeying by night. I'm honestly not sure what they hope to gain by night travel. Many of the Dark Lord's agents can see in the dark, and Gollum likely sees better in the dark than in light. And the presence of orcs and a dark flier who's presence touches Frodo's Nazgul-inflicted wound definitely puts true to the lack of safety in night travel.
Portaging is hard work. We'll just leave it at that. No one's happy with that part of the trip.
On approaching of the Argonath, the Pillars of the King, we perhaps truly see Aragorn in his royal visage for the first time. His whole affect changes: his voice seems strange, his posture strong and erect, and a light in his eyes. In claiming his heritage he assures the safety of the Fellowship in the shadow of the Gates, but then the moment is past and he withdraws back to a state of questioning and uncertainty. I think Aragorn and Boromir are designed as studies in opposition. At the core, they want the same thing, the safety of their people and the vanquishing of Sauron. But they have different relationships with power and even entitlement. By and large, Aragorn stands true against the Ring, while Boromir becomes more consumed by the Ring and his own self-doubt.
At the end, I find a small bit of amusement. I know it's not meant as particularly humorous, but i can't get over the final sentence of the chapter. "The last stage of the Quest was before them."
Looking briefly at the film, Jackson found some beautiful locations to shoot the travel down the river, but traveling at night and the discovery of Gollum is removed. Instead we get cuts of orcs seeking the party, with no daytime river ambush. The Argonath stand magestic and large, but without the dark gate that so inspires fear in Sam, nor without the change in affect of Aragorn. We're also saved from the portaging, and Aragorn has set the plan for travel that Boromir espouses in the book, that Gimli's objects to using Aragorn's written word.
Things will come to a head soon.