It stands for Sun Set Beach. The au natural part of CSS. There is a nice beach area, as well as lots of room around the pretty good size swim-up pool bar. I have often wondered why they use three letters instead of just SB. Sunset really could be just one word rather than two seperate words.
Sunset Beach. It is the 'au-naturelle' part of Couples Sans Souci and the best place to relax and unwind with your SO (significant other). Try it, you'll love it (but don't take any clothes to wear! ;-))