Hi Bringel
I was there in April, dived Nosy Be and the area around.
Water was between 26 at 15meters and 32 on the surface, I used a neoprene long sleeve rash-vest, board short and plenty of sunscreen, and dived for hours at a time.
just remember a pad to protect your chest when loading, I used a flip-flop.
Enjoy your trip, and please bring back tons of pictures and stories!