This is a very good science fiction novel. The scene is a system with 2 inhabited worlds. There is an inhabited planet and a moon around the planet which is entirely ocean. Markedly different societies occupy these worlds. The planet is a largely traditional human society; capitalist, patriarchial to a large extent, traditional forms of government, and physics based technology. The inhabitants of the aqueous moon are females who reproduce via parthenogenesis, have a very egalitarian society, and rely on sophisticated biotechnology. The book is about the clash of these two cultures. The themes are rapacious patriarchy versus feminism, hierarchy versus egalitarianism, ecological integration versus exploitation of the natural world, and coercion versus pacifism. This is a well written and enjoyable book. The author does a very good job of depicting ecology of the aqueous moon. Defects include the fact that the contrasts between the two societies are too black and white, and an overly elaborate plot with unnecessary prolongation of the book. This book is also somewhat derivative. There are themes and ideas drawn clearly from Ursula Le Guin's great utopian novel, The Dispossessed. This book is still superior to most science fiction but because it has pretensions to greater value, invites harsher criticism.