Hi rlitt,
You've thus far received over a dozen replies, yet not one has asked what time(s) of year you are interested in, a matter you did not specify in your post.
This is rather important as temps can reach a low of 77 in mid-winter and high of 86 in late summer, although the expected range is more like 79-84. Even so, for most folks 79 means different thermal protection than 84.
It is also important in that thermal comfort is quite idiosyncratic. Asking a random audience if you need to take a wetsuit and what type will yield a variety of responses, as can be seen in the present thread, e.g., "swim trunks & a T-shirt" to "7 mm wesuit."
To put it in perspective, below is a piece, in part, from my June '00 "Ask RSD" column in "Rodale's Scuba Diving":
"Have you ever been out on the street in the spring or fall and noticed people wearing everything from shorts & T-shirts to full coats with hats & scarves, all apparently in comfort? Well, things are no different underwater. This comfort is highly variable among individuals depending on such factors as percentage of body fat, age & tolerance to thermal discomfort. Other determinants, like how many dives a day over how many days you are planning, are also important. When you ask "What wetsuit should I wear?, you'll get answers ranging all the way from "just a bathing suit" through "5 mm full."
The question is better asked: "What water temps can I anticipate at my destination?" You'll receive a pretty accurate answer to this, and then can decide what's best for you based on your personal thermal comfort needs.
It's always a good idea to come thermally prepared, just in case."
Because of the healthy reefs & currents in Coz, it's always a good idea to wear a full covering of some sort, although whether that is a simple diveskin or a substantial wetsuit in part depends upon time of year.
Is there a particular time of year in which you're interested?
Best regards.
DocVikingo