I have a perverse need to DARE the damn water to leak out the edge of the image if it can. So far, hasn't happened, but I want to see it TRY! I sort of try to keep things level, but my head is un-level enough that close is as close as I get sometimes. As for rules of composition, I don't believe in 'em. Sometimes I end up with the water/horizon at a third or two thirds, as the rules would indicate. But if there's something else in the frame that says leave it halfway, or make it 6/16 or 10/17 or whatever, that's where it ends up. If you're ever planking in one of my shots, I promise to have your face down self at 1/3 or 2/3 - otherwise, no promises!
Not to worry - I'm enjoying it immensely and I have a feeling I'm gonna enjoy the second half in Positano even more than I'm enjoying the first. It would be a hard place NOT to enjoy...
-Ray