Finding nice beach/ DW themed invite wording is a total pain!  I searched and searched and to be honest I have no idea where I got all the following ideas from!  So to help you out here is what I found and lastly what I used =)

Wedding invite wording ideas!

(1)
Walking on the beach together,
Hand in hand we'll be forever.
_____
&
______
 Together with their parents
invite you to join them barefoot on the beach
as they pledge their eternal love
(Date, Time, Location)

(2)
Ocean waves will do the clapping.
as our vows we will say
The sky will be our canopy
on this our wedding day

Please join us as we exchange vows on
(Date, Time, Location)
____
&
____

(3)
As unique as a seashell
as deep as the sea
As eternal as the waves
our love is meant to be.

It is with joy that we,
____
&
____
Invite you to share
in our happiness
(Date, Time, Location)

(4)
Sea of love.....
As precious as the ocean's treasures,
too strong for anyone to measure.
Please join us as we
____
&
____
are united in marriage
at an outdoor ceremony
(Date, Time, Location)

(5)
A beautiful beach
A clear blue sky
A love united
With waves crashing nearby
____
&
____
Invite you to join us
(Date, Time, Location)

(6)
Each hour, each day, each year
We grow as two, yet as one.
We grow apart, yet together
Forming an eternal love
We
____
&
____
Invite you to share in
our beach wedding
(Date, Time, Location)

(7)

Our wedding will be a fairy tale....
a dream without end.

A beach with a beautiful sun...
Please join us on the sand.
____
&
____
Invite you to share in the joy
when they exchange vows
and begin their new life together.
(Date, Time, Location)

(8)
As the sun goes down
The will join together hand in hand
Professing their love for one another
And leaving imprints in the sand
Now and forever
Partners in life
Under palm trees swaying
They will become husband and wife
____
&
____
(Date, Time, Location)

(9)
In a distant land
Memories will be made
Glasses will be raised
Songs will be sung
Two hearts will become one

RSVP Wording

(1)
Yes, have a margarita ready!
No I sunburn easily!

(2)
Please Sea if you can respond
You beach ya we'll be there!
Sorry must Wave your invitation

(3)
Yes, You beach ya we'll be there!
No, we're all tide up and we must wave your invitation

(4)
Yes, we have our swimsuits and dancing shoes packed!
No we can't make the trip but wishing you well.

My invitation wording

Wedding-
Walking on the beach together
Hand in hand we'll be forever.
Ashley & Josh
Invite you to join them barefoot on the beach
as they pledge their eternal love.
(Date,Time, Location)
RSVP -
Yes, have a margarita ready
Save me _ beach chairs

No I sunburn easily

AHR
Ashley & Josh
Will join hearts and hands
on the 15th of May  Two Thousand and Ten
In a private ceremony on the shores of Grand Cayman
 
Please join us to celebrate their marriage
(Date, Time, Location)

RSVP-
Wouldn't miss it
_# of guests
Will be there in spirit