Symbolism, Imagery, Allegory
Who uses a can opener as a symbol? Hemingway, that’s who. Nick is very thorough about how he executes the various tasks of camping. We get a ridiculous amount of description when it comes to things like laying out his sleeping bag:
When he had the ground smooth, he spread his three blankets. One he folded double, next to the ground. The other two he spread on top. (I.24)
Wow. That’s three (count ‘em: three) whole sentences devoted to sleeping gear alone. How are we supposed to analyze a story that reads like an REI ad? Well, similar to how we see the river used as a symbol, we also see that physical tasks like pitching a tent and opening a can provide Nick with a degree of comfort:
He hung the pack up on the nail. All his supplies were in the pack. They were off the ground and sheltered now. (I.28)
He liked to open cans. (I.35)
There is also a physical aspect to this: just like how Nick likes knowing that the river is physically there, he also seems to like tasks that he can perform with his hands and then see, like making sure the tent is right, or knowing that his pack is sheltered. You might even say that Nick’s behavior is about being in control of a situation, even if that situation is opening a can, because we sense that he might not be fully in control of his emotions.