Aronnax wakes up the next day, groggy and confused, in his own room. He finds the door unlocked and ventures out onto the platform, where he finds Ned and Conseil.
The three try to figure out what happened, but nobody knows anything.
They can't see anything on the seas around the ship. They head back down.
After a long absence, Nemo appears in the salon; he looks worn out and sad.
Finally, he asks Aronnax, "Sir, are you a doctor?" (1.24.10).
As it turns out, he is.
Nemo asks him to treat one of his sailors. Aronnax says yes, so they head down to a cabin near the crew's quarters.
There, Aronnax finds a sailor with his skull broken and his brain showing. Things aren't looking too good for this sailor.
Nemo claims that the man was hurt when a piece of the engine broke and hit him.
Aronnax is skeptical, but that doesn't change the fact that he can't help the man. He tells Nemo that his sailor will be dead in a couple of hours.
With that, Nemo sends Aronnax away.
The next morning, Nemo asks Aronnax if he wants to go out on another expedition. He says yes, and soon he finds himself surrounded by beautiful coral.
After walking for two hours, Nemo stops in a "forest" of petrified trees. Nemo's sailors surround their captain.
Aronnax notices that some of them are carrying a long object.
Aronnax, Ned, and Conseil watch as one of the men begins digging a hole in front of a cross. Suddenly Aronnax realizes what's up: they're burying the injured sailor. Nemo's got an underground cemetery down here.
When the coffin is buried, they make their way back to the Nautilus.
Nemo confirms that the man died during the night, and that he's been buried along with others who have died on board the Nautilus.
"At least your dead slumber tranquilly, captain," Aronnax says, "out of the reach of sharks."
"'Yes,' Captain Nemo repl[ies] gravely, 'sharks and men!" (1.24.76-7).