St. Lucia is a great place to dive. Due to the warm water I only dove a .5mil fullbody suit just to keep the jellyfish off and a pair of shorts. Anything over that and I would have gotten to hot as the water was in the 80’s. I would suggest getting a cheap underwater camera just to take some pictures as it it beautiful down there. If you look at my profile I have picture links to all the places I dove when I went on my 2 week wedding cruise. Antigua does not have any real diving if I remember correctly.