chrpai:Normally good advise, but BB's typically does 3-4 dives a day ( 18 dives total on a 1 week trip ), and most of them are very shallow. ( <30' ). A 7mil really is way overkill.
Yep - if anything, a 5mm would be fine, but why not just get a 1 mm or a 0.5mm and you can wear the 1 underneath the 3 if needed. Works great for me. But as already mentioned, only you will know your own cold tolerance. This setup works fine for me, but others would argue that my idea of cold is much different than some.