What a pity: Photos 1, 4 and 5 will oh-so-soon be all "empty" for all the water will have run out on the left of the frame - in other words: mind your horizons, keep them straight, don't get them crooked, least of all with water photos .
I'm not sure I am overly fond of your play with short DOF in 4 and 5, particularly with regards to the blurred foreground in 5.
In 4 it is not bad, points at the texture of the sand, but I still miss the tip of that tall palm tree in the background, blurred as all the palms may be.
hmm. hadn't thought of the horizons. I suppose I can just fix it in editing, and a slight crop! =)
#4 was a matter of scope, I suppose. I was at minumum focal length, and didn't want to back up any, so I sacrificed the top of the one tree. Also, it was quite windy, so the DOF effect is magnified by the motion of the trees (minimally, since this was a fast shutter, but still there! lol)
I guess I wasn't thinking much of DOF while shooting. I was more worried about proper exposure, and I wanted the fastest shutter I could manage because of the wind, and moving animals. I also didn't want the water to smooth out at all, I wanted ALL the ripples. Fastest shutter, obviously, points to a wider aperture, and less DOF. oh well! I'll try differently next time.
You seem to be lacking subject matter here. They aren't doing anything. There are a lot of variables involved. However, it does get easier, and more fun as time goes on. So don't give up.
Of course you can straighten them in PS or any typical photo editing software. Other than that I like your use of putting the camera on the ground ( or however you do it ); I especially like 2.