For the ladies:
Pick materials that won’t cling to your body in the heat - linen, chiffon, organza and cotton blends
Choose colours that are bright and vibrant to embrace the sights and sounds around you. Selecting something with a pattern is a plus!
If it’s a formal ceremony, wear a longer gown. Semi-formal or casual could call for shorter dresses and even maxi dresses
Flip flops or sandals are an option, as long as they’re on the dressier side
For the men:
Pick pants and shirts made of linen - it’s super lightweight and comfortable
Choose a jacket and pants that are light coloured, such as white or beige, with a bright coloured shirt
Don’t worry the tie since the venue is non traditional and can make you feel restricted in the warm weather
Don’t wear shorts! Unless it’s explicitly stated on the wedding invitation
Flip flops or sandals are an option, as long as they’re on the dressier side
Sources: http://destinationweddingdetails.com/beach-wedding-attire-tips.html