The most noticeable thing is the moiré patterning in the second photo, and some grain in the clouds. Try turning down the sharpness a bit. Scroll this video to about 8:30 for a good explanation on sharpness and artifacts in your images
The first image seems pretty good, or at least looks like I would expect. I have a P4P, but I've noticed a big difference in how the camera reacts to being aimed right at the horizon vs tilted down slightly. Asking for advice led me to stop using auto settings in general. But ISO 100 should be good as long as you can change the other settings to get a good exposure.
I've found that some things like trees, fields, and beaches can just be prone to problems because they actually are textured and grainy, so I think sharpness is a good place to start.