Kenran Butousai: The Mars Daybreak

The series is set on a fictionalized Mars, where the entire planet except for its highest peak, Olympus Mons, is covered by water and ice. Consequently, the people living on Mars have built "city ships" adapted to this Martian ocean environment. Because Mars possesses abundant water resources, the Earth government regards it as a key development base, but this has also drawn them into an interstellar war. Caught in the crossfire, Mars falls into unprecedented economic depression, leaving its inhabitants suffering. In response, several groups of pirates and rebels emerge to oppose the oppressive Earth government that controls the Martian residents.