This is book 16 of the "Aubrey-Maturin" series.

This note contains spoilers for the book.

Underwater volcanos! Shooting lava bombs through the air! Also weird French idealists, and Americans, and people with a very different sense of honor from Stephen's. Nearly everybody is prepared to found their utopia at the expense of the native Pacific Islanders (though, to be fair, they of course believe that their utopia will suit everybody admirably).

And Stephen does get to South America, and O'Brian has to frustrate him, I guess, since there wasn't in fact a successful uprising then. We're in 1813a anyway, why worry about that? But it does make for more things to keep track of.