A Door Into Ocean

A science fiction novel written by Joan Slonczewski. The ocean planet of Shora is invaded by outsiders from Valedon who wish to develop the planet. The native Sharers spend much of the book trying reconcile their pacifism with the need to protect their planet.

Tropes used in A Door Into Ocean include:

Achilles' Heel: Since the Sharer philosophy says that everything is alive, or has been alive at some point, some Sharers go insane when they encounter stone- since it is "dead," it violates their entire world view.
Actual Pacifist: The entire Sharer population.
One-Gender Race: The people of Shora are all female.
Organic Technology: The Sharers' technology.
Perfect Pacifist People: The Sharers.
Single Biome Planet: Shora, which is entirely ocean.
Super Not-Drowning Skills: The Sharers have bacteria that live under their skin and help them store large amounts of oxygen. The bacteria also turn them purple.
Synthetic Plague: What the invaders are afraid will happen, due to the Sharers' use of genetic engineering.
What Measure Is a Non-Human?: One of the main concerns for the Sharers is determining whether the invaders count as human according to their philosophical system. If they are, then their pacifist beliefs keep them from harming them. The invaders, meanwhile, call the Sharers "catfish" and don't acknowledge their humanity.