The Sand Ceremony offers beautiful symbolism and commemorates beach weddings perfectly.
Here is some possible verbiage, but I always custom-write my ceremonies to fit the couple:
BRIDE and GROOM you have just sealed your bond by the giving and receiving of rings and this covenant is a marital pledge between two people who agree that they will commit themselves to one another throughout their lives. The most beautiful example of this partnership is the marriage union. Today, this relationship is symbolized through the pouring of these two individual containers of sand. One, representing you, BRIDE and all that you were, all that you are, and all that you will ever be, and the other representing you, GROOM, and all that you were and all that you are, and all that you will ever be. As these two containers of sand are poured into the third container, the individual containers of sand will no longer exist, but will be joined together as one. Just as these grains of sand can never be separated, our prayer for you today is that your lives together would take longer than the time it would take to separate the individual grains of sand.