A Door Into Ocean by Joan Slonczewski

1986 Arbor House book club hardcover edition in good condition. Some light wear on dust jacket extremties.  Bright white pages.  Cover art by Don Walotsky. A classic of feminist science fiction. 
John W. Campbell Memorial Award for Best Science Fiction Novel (1987)
 
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.
 
Joan Slonczewski's first novel, Still Forms on Foxfield, made the Locus list of distinguished first novels and was a nominee for best novel of the year. She continues the tradition with A Door Into Ocean. 
 
Thousands of years in the future in a distant part of the galaxy, lies the planet Shora, entirely covered by a world-spanning ocean. The huge and complex ecosystem of Shora is inhabited by Sharers, an all-female race who reproduce by parthenogenesis, without males. The Sharers are immensely sophisticated in the life sciences, but have eschewed all unnatural technology. Over millennia of isolation, they have developed a complex philosophical and ethical system, idealistic, communal, and pacifist. 
 
But now, as interstellar civilization rises again, the Sharers are faced with a technologial and cultural invasion of a man from space. They must develop a system of peaceful coexistence. Two of them travel to a nearby planet in the hope of gaining a better understanding of the male invaders. There they invite a young man, Spinel, to return with them so they can learn from each other. This is urgent, for in the space of a few short years,  the traders who have set up shop on Shora have been reinforced by armed men from nearby Valedon, of which Shora is a satellite, and are preparing simply to take over. 
 
So begins a war, protracted and graphic, in which one side cannot fight because the concept is inconceivable in their philosophy; a war in which the one fragile contact between Merwen, the Sharer, and Spinel, the man from Valedon, might well provide the only hope of true communication between two radically different cultures.
 
Every few years, a new author in the science fiction field contributes a major work to the central tradition of world building. The planet Shora is such a contribution, an ecological system that deserves comparison with Frank Herbert's Dune.
 
- From the DJ