The torso is 3mm with 2mm on the legs and arms.  I'd get it, and then buy a
drysuit ;)

Jon

Can't speak for O'neill and this particular model, but I have a custom
3/2 suite and I love it.  Great for Floroda and Caribbean conditons.
I recommend a hooded vest that can be worn with it for colder times.
(Mine is 5 mil body, 3 mill hood.)

I'm not a windsurfer, but -- does a wet suit for surfing have a different
cut and/or other different features compared to a dive suit?
I'm not certain that on suit will work well for both activities.

I use an O'neill 3/2 Reactor in SoFL (dives of up to 90 minutes) and
for short (<45 minutes) training dives in the springs. I had a Mares
3mm before that. I do not get cold faster in the 3/2, and it is
considerably more comfortable. I particularly like the way the arm and
leg ends are made in the O'neill.

I don't know the particulars about the O-neil, but I've been diving with a
full 3/2 Bare for a few years. The torso is usually 3m, while the arms and
legs are 2mm. I've used it in Cancun, Cozumel, Tobago, Thailand, DR, Cayman
and was never uncomfortably warm, but then again, I don't like diving cold.
The suit also gets used in Northern Ontario - but only in the summer. The
divers up here usually go for a full dry suit for spring/fall dives. I did
my openwater in early summer in a 7mm and it got cold fast when you hit a
thermocline.

As for windsurfing, I've used mine in a pinch when travelling - but I do
have a surf specific suit for windsurfing. In the Windsurfing suit (Neil
Pryde) - the arms are cut a bit looser on the length and under the pits. The
curvature is also intended to accomodate the raised arms. The suit also is a
smooth finish without the fabric on the outside to reduce the cooling effect
of the wind. The dive suit will work, but you'll find your arms tightening
up and getting tired quicker.