Destination Formal. Think of the elevated evening-wear you would step out in if you were going to an upscale restaurant or party while on vacation.
Summer colours encouraged! Please be mindful that our wedding venue is on the beach.
While you won't be required to walk on the sand, we suggest that you opt for platform or wedged heels instead of stilettos. 
Men: wear a light-weight sport jacket (any colour) and/or a button down shirt with light-weight slacks; jackets and ties are optional. 
Women: long flowy evening dress, or even a dressy midi or short length dress if you prefer!