Having been in the Caribbean I know how the famos turquoise waters there look, feel and smell. But you don't have to go all that way over there. Over here at the Costa Blanca you have it just the same way for less money especially when you go in the Off-season as it is now. Hotel prices drop drastically and you get real good offers right now. The teperature is good, with cool nights and warm or even hot days about 28° C.
Yes, and the water had enough time all summer long to keep warm and cosy. Last year I even went bathing until October 31st, the temperature being still 22°C. Yes that is the Mediterranean Sea in the South of Spain. Traveling there is easy with the new airport in Alicante and a busride to either Benidorm or the other nice places. You may also think of renting a car, which you should do online from back home for the best rates ever.
I wish you a happy holiday. May all your dreams come true .