There's much excellent advice here so far, but I'd like to throw my hat in the ring too, if I may.
The EXIF data is in both your photos. In both photos the ISO was 200. I had guessed it was at 400 or below due to the lack of noise. Brian is right, there really isn't any pixelization. In the top photo the settings were: ISO=200, shutter speed=1/200, f/11. Matrix metering was used. The curious thing about the shot, the EXIF data indicates the flash fired. Keep the flash off as it can't add anything to this shot.
The white in the ocean doesn't seem to have much detail, but I don't think the dynamic range of the scene particularly exceeds the capability of the camera, as there is plenty of detail in the foreground, the water, and the rocks in the ocean.
I think Sal is certainly right that the lighting is very uneven, but I think there is an identifiable reason for that. Getting an exposure setting with the dynamic range in the scene isn't going to be easy unless the range can be reduced.
Using Martin's suggestion to spot meter different areas to help you compute your exposure settings is a good idea and can result in a better exposure, (through the use of manually setting your exposure after you spot meter different areas of the scene) but I doubt that will really get the image to match what you saw, as the combination of the human eye and brain produces amazing performance, far better than any Nikon or any other brand camera. Actually, in this case matrix metering should produce very good results as the way it works is well suited to this scene, in my opinion.
I would suggest you begin to learn about exposure and experiment and practice getting off auto exposure, and begin to try aperture priority, shutter priority and manual exposure modes. I think you'll like the results once you get used to them and in the priority modes how you use exposure compensation to correct problems in metering a scene.
Brian's suggestion to use a polarizing filter is exactly what I would have used. I believe most of the over exposure of the ocean portion of the scene comes from the significant light reflection off the ocean. If you can remove that via the polarizer, you immediately reduce the dynamic range of the scene and enhance your camera's ability to capture it well. Using a polarizer would probably negate the need for any substantial postprocessing.
Postprocessing can also help a great deal, now that the photo is "in the can." I did a little postprocessing in Photoshop on your photo. I created a mask of the ocean/rock area of the photo. I used levels to be fast, but curves would be even better to adjust the masked area which shows as overexposed. I then added a touch of overall saturation, contrast, and tweaked brightness a tad. See what you think of my rendition. It's a bit crude, but I didn't have much time to work on it this morning, but you can get the idea.