What to pack for the Bahamas ?

I'm going to the Atlantis resort in the Bahamas in July and I've never really traveled to any islands before so I have no clue what to pack. All I know right now is 70+ SPF sunscreen(lol). What do you pack for a place like the Bahamas ?? How many bathing suits should I bring also?? Going for 8 days. I feel like I'll end up being over dressed because I love dressy clothes. Help please :)