some chunks of land were deformed oceans the rest were floating islands, I have no mods enabled. Ocean structures were also generating on land showing that the area was supposed to be an ocean.
An endless void also generated below without any bedrock layer.
Is this still an issue in the most recent versions (currently that is 1.13.2, or the latest snapshot 19w02a) of Minecraft? If so, please provide the seed and coordinates.