Oceans are a biome created by the Ocean Giant's Create Ocean ability. Each use of this ability generates 9 patches of Ocean. Oceans can be partially or entirely raised back to ground level by using the Rock Giant's Raise Mountain ability. Oceans can also be extended by using Create Ocean adjacent to the existing one. A single body of water cannot be smaller than 6 patches. If Raise Mountain is used in a way that the body of water would become 5 tiles or less, the rest of the water will raise with it.
The ocean biome is unique in that it is not able to host any Plants or Minerals but it is still able to host Animals. Nomads cannot create villages on oceans, but a village adjacent to an ocean can create special ocean-only projects, such as the Fishing Docks.
Ocean patches hydrate all ground-level patches on either side of them. The amount of patches hydrated on each side is equal to the size of the ocean + 4. Therefore, a standard 9-patch ocean will hydrate 13 patches outwards on both sides.