A little background, simplified: much of the Earth is covered in water. Because of the way the continents are arranged, that water is divided into five oceans: the Arctic, the Antarctic, the Indian, the Atlantic, and the Pacific.
Aronnax finds himself traveling through that last one which, as its name suggests, is the most peaceful of the oceans.
In order to mark the beginning of their journey together, Nemo calls for the Nautilus to surface. He and Nemo head up to the platform in order to determine the exact location of the vessel. Standing on the surface of the sub, Aronnax understands why it was mistaken for a sea monster, what with its metal plates and the two bulges—one for the cockpit and the other for the light—on either end.
The day is clear, and there's nothing to see but endless ocean. Nemo takes some measurements and then they head back down to determine their location.
They're three hundred miles from the coast of Japan.
It's noon on November 8. It's time for their journey to begin.
With that, Nemo leaves Aronnax to his own devices.
Aronnax spends a while wondering who the heck Nemo is. Is he some kind of vengeful lunatic? Is he a genius cast out of a society that can't understand him? He doesn't know.
After an hour of that, he takes a look at the huge map laid out on the table.
He notes that they're traveling on the "Black River," one of the five main ocean currents. (You may have heard of another one, the Atlantic's "Gulf Stream.")
At this point, Conseil and Ned come to join Arronax. They're astonished by Nemo's "museum."
Aronnax tells Ned everything he knows about the Nautilus.
Ned wonders, though, how big the crew is. Maybe they're electric, he jokes. Still, he does want to know… probably so that he can decide whether or not the three of them can take over the Nautilus.
Aronnax tries to calm Ned, telling him about how much they'll be able to see while traveling under the sea.
Ned doesn't understand how they're going to see anything, considering the fact that they're stuck inside of a big metal cylinder with no windows.
The lights in the room go out, surprising Aronnax and company. They hear a sliding sound.
Ned thinks something has gone terribly wrong.
Suddenly, two bright lights turn on, lighting up the sea outside. Two large panes of glass—portholes of a sort, one on each side of the room—separate our protagonists from the water.
Now they can see miles into the see. Everyone is thrilled.
Aronnax thinks he can understand why Nemo likes being alone down here.
Ned wants to know where all the fish are.
Conseil and Ned begin talking about fish. See, Conseil knows all about fish, scientifically speaking, but he doesn't really have, well, hands-on experience with the buggers.
So when Conseil runs through the different classes of fish, all Ned can do is tell him whether or not those particular specimens are tasty. That's some real tactile knowledge right there.
The three men watch fish for two whole hours. Ned and Conseil team up for a little game of spot-that-species: the harpooner names the fish, and the classifier classifies them.
Eventually, the electric lights come back on in the sub, and the windows close.
Aronnax waits for Captain Nemo to arrive, but he's a no-show.
Ned and Conseil head back to their cabin, and Aronnax heads back to his. He eats dinner alone and spends the rest of the evening writing.