Before you start eliminating parts of the image and worrying about distortion, I would work on some other technical issues...try to select the pool with or feathered lasso, or somesuch, and then try to bring out some detail in the pools in the foreground..this is easily done and will make a huge difference what you are trying to do with this photo..a photo of the tide pools.
i dont think it's to bad, compositionally, right now.