Twenty Thousand Leagues Under the Sea by Jules Verne

Three adventurers set out to K*ll a sea monster, but all is not as it seems. Out in the vast expanse of the Pacific they find not a beast but a submarine - the Nautilus, an advanced craft captained by the enigmatic Captain Nemo. Captured and hauled aboard, they accompany him through coral reefs, shipwrecks, and ancient ruins. There they hunt sharks, and battle giant squid, not realising that the greatest danger is Nemo himself, who will stop at nothing in his quest for vengeance.