Great job! Deserves technical merit. However, a water shot, or even a shoreline shot, or even something that belongs or comes from a beach, does not always mean 'beach' in my opinion. And meeting the challenge, to me, is the first and most important thing, if that isn't done, then anything else is unimportant. Doesn't mean it's not a beautiful and creative shot, because in this case, it absolutely is! I do love it! I went back and forth on how to score your pic, but I do vote low for those that I don't think meet the challenge, so to be consistant, I am voting this lower than I want for the reasons stated above.
Okay even though I feel this doesn't meet the challenge I still have to vote it a 9 because, damn it, it really is a great shot. You composition perfect. Good job.