Perhaps this could provide a few new ideas that may be adapted to use with Victorian submersibles:
Murray Leinster, Creatures of the Abyss
Audiobook:
I think Nemo would say something like this about “his seas”:
To me the entire story feels like it would have fit much better if it had taken place in a Victorian setting. It’s got maritime War of the Worlds potential.
Thoughts?
PS. Or Nemo could create a spaceworthy “Nautilus” and end up following the big surge to colonize Mars. He could work as a “free trader”, or do the same plundering work he did with the Nautilus had done on Earth, or he could build an entire fleet of airships and fight for the Martians.