When I went to mexico, a friend suggested I take 2 bathing suits (as if one isnt hard enough to find!) ...that way you can wear one one day, wear the other one the next...and not worry about wearing a wet swimsuit. I couldn't find a second one, but it was a good suggestion b/c it felt kind of icky wearing a wet one.
Other than that:
bathing suit wrap thingy (if want)
sunscreen
sunglasses
deodorant
camera
journal
toothpaste/brush
(shampoo/soap usually provided, or take your own)
imodium for 'upset stomach'- you might need this and its super expensive there!
aspirin
lock (most places have those little safes in your room, but I personally don't trust those - heard some stories abt them-and brought a combination lock, so I could stick my passport etc in a makeup bag thingy and lock it...anal - yes!)
Yay, you're wedding is coming so close!!!
