When Aronnax wakes up, he's in the cabin of a fisherman, in the remote Lofoten Islands (off the coast of Norway). Ned and Conseil are there too.
Aronnax waits to head back to France. The ferry to the mainland doesn't come too often.
So there he is, working on his manuscript… which happens to be the book we've just read. It's all true, he says; "[n]ot a single fact has been omitted" (2.23.3).
Aronnax isn't sure anybody will believe him, but that's alright. He knows he's traveled—and here's the title line—20,000 leagues under the sea in under ten months. He's been through the Mediterranean, the Red Sea, the Pacific, Indian, Atlantic, Arctic, and Antarctic oceans.
And what is he left with, other than some great stories? A whole lot of unanswered questions. Like: what happened to the Nautilus? Is Nemo still kicking? Is he still killing? Will we ever know where he's from or why he does what he does?
Aronnax hopes so. He hopes Nemo is still alive. He hopes Nemo will stop hating on everyone so much. He hopes he'll stop seeking revenge. He hopes he'll keep exploring. In any case, Nemo's an extraordinary man. Aronnax knows this for sure. He's got firsthand experience. He's spent ten months down there with him, under the sea.
Only Aronnax and Nemo can answer "that question which the Book of Ecclesiastes posed 6,000 years ago, 'hast thou walked in search of the depth?'" (2.23.5).