"Vingt Mille Lieues Sous Les Mers — Part 2" by Jules Verne is a novel published in 1869-1870. Three castaways find themselves prisoners aboard the Nautilus, a technologically advanced submarine commanded by the enigmatic Captain Nemo. As they journey through ocean depths, discovering underwater forests, sunken treasures, and battling giant squids, Professor Aronnax grows increasingly curious about their captor's dark past. The captain harbors a terrible secret and seeks vengeance against a mysterious nation, using his vessel as a weapon of war.
Wikipedia page about this book: en.wikipedia.org/wiki/Twenty_Thousand_Leagues_Under_the_Seas fr.wikipedia.org/wiki/Vingt_Mille_Lieues_sous_les_mers