Beach weddings offer a beautiful setting for a wedding. It also has a very close connection to nature for those of you feeling a special connection to the environment around us. Getting married on the beach can also be made very casual and many brides choose to get married in a lighter material dress (also due to the weather).
If your wedding ceremony is going to be lengthy you may want to consider offering your guests parasols or getting married under a tent and having water close by especially if the wedding ceremony is taking place on the beach in the middle of the day. With getting married close to water you also need to consider the tied so that you will not be drenched in water by the end of the ceremony or having to move all your guests up the beach as the ceremony progresses.
Some wedding resorts are right on the beach, making your wedding ceremony location easy and convenient to access for yourself and your guests. If you are getting married on a beach and you are concerned about it being a public beach ask the hotel wedding planner what they normally do in those cases (just so that you do not have a hundred strangers joining your wedding ceremony, unless you are shopping for some extra guests).
As casual as a beach wedding can be with soft, thin wedding dresses and bare feet you can also still make it formal as far as attire goes, it is all up to you. But you may want to consider comfort since more formal and traditional wedding dresses and suits can be fairly warm and thick, you don't want to pass out before your say your "I do's". Whatever you decide make sure that you note the dress code on your wedding invitations so that your guests know what to pack and prepare for.