After getting more stones tossed at them and making some racist remarks (e.g., "'Is it monkeys?' exclaimed Ned. 'More or less,' said Conseil; 'savages'" (1.22.5-6)), they run for the boat. By now, arrows are falling on them too. Still, Ned manages to grab his pig and kangaroos. And we thought we were attached to our food.
The group jumps into the boat and pushes off. A hundred "savages" are making their way into the water after them. Off in the distance, Aronnax can see the Nautilus, completely deserted.
When they get on board, Nemo greets them. He doesn't seem too disturbed by the whole cannibals-trying-to-kill-them-all affair. In fact, he's perfectly content to play the organ.
Aronnax goes back up to the platform. It's night now, and he can see a bunch of fires blazing on the beach. The natives definitely haven't given up.
Nothing happens during the night, but the next morning, Aronnax can see five or six hundred natives on the beach. They're within shooting distance, but Aronnax doesn't do anything. "When dealing with savages," he writes, "it is better for the Europeans to riposte [counter-attack], rather than attack first" (1.22.39). Dude's not exactly enlightened when it comes to race.
Anyway, Aronnax decides it'd be a great idea to go up on deck and look for some cool shells floating in the shallow water. Because he's bored, even in the middle of all of this drama. He manages to find a really cool shell. Its swirl goes counterclockwise instead of clockwise, which makes it super rare. Unfortunately, a native throws a stone that breaks the shell in Conseil's hand. Sucker.
Conseil flips out and shoots at the native, but he misses.
The situation gets worse. The natives surround the Nautilus in canoes. They shoot arrows at Aronnax and Conseil but, like all bad guys, they seem to have terrible aim. The two scientists run down to find Nemo.
Yet again, Nemo's surprisingly calm.
Aronnax tells Nemo that he's scared the natives will swarm the boat when they open the hatches the next day (to refresh the air inside the sub). Nemo still isn't fazed. He doesn't want to kill the natives, and he's certain he won't have to.
The next day, just when the air supply is beginning to get low—and the tide has gotten to the point where the Nautilus can move—Nemo flips a little switch. The natives, who are peering through an open hatch, start crying out in pain.
It turns out that Nemo can electrify the top of the Nautilus; his trick causes pain, but doesn't kill them.
Soon enough, the Nautilus moves itself off the reef and gets back on its way. They made it, yay.