Isso parece ser Daybreak de Marte
Ele atinge todos os pontos principais:
- Ocean terraformed Mars
- Jovem protagonista masculino
- Convidado para tripulação de submarino pirata chamado 夜 明 け の 船 / Yoake-no-fune. Isso traduziria como Navio de Amanhecer ou (como a tradução oficial) Navio de Aurora
With the surface under heavy satellite surveillance, the pirates have been forced underground. Or rather, underwater. Instead of sailing over the waves, they lurk under them in submarines. And the baddest pirates around are the crew of the sub Ship of Aurora.
Which brings us to our hero, Gram River: A young man living on the city-ship Adena. While trying to help a friend get out of a bad situation, he ends up in the middle of a raid by the Ship of Aurora, and thrown overboard when the port is rammed and breached... He is eventually hired on by the crew - https://tvtropes.org/pmwiki/pmwiki.php/Anime/MarsDaybreak
E da Wikipédia:
The ocean-covered environment makes a perfect setting for commercial trade ships and pirates to utilize submarines to make a living. At the same time, the pirates also raid those very trades for personal profit. The most renowned and feared of the pirate vessels is the Ship of Aurora, which makes a habit of reselling its booty cheap so that it can be redistributed to the less fortunate folk. - https://en.wikipedia.org/wiki/Mars_Daybreak