We're not going to hold you back from seeing the ocean that surrounds Cuba as a kind of amniotic fluid that supports and cushions Celia from the shocks and disappointments of her life (bravo for you if you thought of that). But do consider other options when parsing out the meaning of the ocean or water in this story.
For one thing, García associates Celia with the element of water. Remember the unfortunate santera's comment about seeing a "wet landscape" in Celia's palm? She tells Celia that although she has it in her to be consumed by fires of passion, she also has the "water" within her to quench them and thrive. In essence, Celia is the illness and cure rolled into one.
She also finds great comfort in the sea that rolls by her house on the coast of Cuba. Celia sits on the porch at night and looks out over the ocean, lulled by the motion of the water and the starlight on the waves. When she's feeling disturbed, Celia returns to the protective womb of the ocean to balance her mind and senses. (Oh, yes. We did.).
Until, that is, the ocean takes on a new meaning in her later years. A more forbidding and sinister meaning. When Celia thinks of the ocean that rings her island, she begins to see it as a great, impenetrable barrier. It's the thing that carries away her loved ones and keeps Cuba isolated from the rest of the world.
But for all that, the ocean does not frighten or deter her. The last time we see Celia, she's returning once again to the water to release her old identity (in the form of the pearl earrings) into the darkness of the ocean. Perhaps she does it to quench the flames of sorrow and disappointment and to emerge as a new person. And there we did it again—a (re) birth metaphor, just for you.