| Quote #1
Our course for the first four days was, with trifling variations, S. E. and by South; and we must have run down the coast of New Holland. (7)
The information here aims to be accurate, establishing the narrator's location, which makes the big whammy of moving into more fantastic areas all the more jolting. And before you go wondering how accurate this info can be if he's citing a place called New Holland, rest assured—that's just an old-school name for Australia.
| Quote #2
We were, however, well aware of having made farther to the southward than any previous navigators, and felt extreme amazement at not meeting with the usual impediments of ice. (8)
Poe also uses descriptions to show us that the narrator is beyond the realm of explored seas and into someplace new. We get the idea that this guy has done a bit of exploring in his day, but this current adventure for sure takes the cake.
By stressing the unexpected features (i.e., no ice), the narrator opens up the possibility of something really wild and outrageous showing up at a later point. He's laying the groundwork early on.
| Quote #3
All in the immediate vicinity of the ship is the blackness of eternal night, and a chaos of foamless water. (9)
The statement places the narrator in uncharted waters… literally. It also emphasizes the dangers of going where no one has gone before.