A Door Into Ocean (Elysium Cycle, #1)

Joan Slonczewski's A Door into Ocean is the novel upon which the author's reputation as an important SF writer principally rests.

A ground-breaking work both of feminist SF and of world-building hard SF, it concerns the Sharers of Shora, a nation of women on a distant moon in the far future who are pacifists, highly advanced in biological sciences, and who reproduce by parthenogenesis--there are no males--and tells of the conflicts that erupt when a neighboring civilization decides to develop their ocean world, and send in an army.