Windog:
I'm in Noumea at the moment. None of the dive operators have large offices and operate out of portable sheds. You have Iatock Diving which is at Baie de Moselle. The other two that I have seen, Alizee Diving and Abyss Diving are at Port du Sud, in Baie de L'Orphelinat. BTW, if you like spearfishing or freediving, Marine Corail and another shop in city of Ducos had so many freediving fins and wetsuit. Hard to find shops like these here in the US.
I used Alizee Diving, which uses a very fast boat powered by twin outboards. We dove at the Passe de Boulari and at another reef, in relative close proximity but with a much shallower profile. Inclusive of the dive gear, I believe I paid 12,000 francs (XFP or CFP) . That's about $120 dollars, which isn't bad at all considering I pay $90.00 for a boat trip, without tanks and without gear, here in California. Alizee Diving does provide Nitrox and I opted to use 32%. Alizee Diving provided Scubapro BCDs (equivalent of a Scubapro Pilot), Aqua Lung 5mm hooded full wetsuits, and MK2 with C300 regulators. The water has been low to mid 70s so you do need more than a 3mm. Bring a water bottle if you need it, otherwise expect hot tea with cookies. Personally, I liked that so much that I'm buying a thermos when I get home and hot tea will be my warm up drink between dives. Satoshi and a lady, whom I believe is his wife, are the owners. Although their English are not the best, either can converse. They are both warm and extremely friendly.
Visibility at the Passe of Boulari is as far as your eye can see and it gets extremely deep as you are on the outside wall of the barrier reef. Some sections have lots of coral, while other sections are devoid of any coral. Saw lots of grey and black tip reef sharks, cora trouts, unicorn fish and Manta Rays. On the shallower dive, the reef's coral structure was vibrant and alive with all the coral fish you expect to see, groupers, parot fish, trigger fish, damsels, etc. I even saw a Lion Fish. I snorkeled at L'ilot Maitre, Plage de Nenon and at the beach in front of the Koulnoue hotel in Hienghene. Plage de Nenon was dreadfully shallow with cave diving silt out visibility. L'ilot Maitre was shallow but the reef had quite a bit of good life. At the Koulnoue, the reef was but 20 yards from shore and I found myself i 30ft of water easy. Not a lot of fish life but the coral was beautiful and vibrant. Be mindful that stonefish are present in the rocky bottoms.
Be aware that everything, apart from restaurants and gas stations close between 12:00 & 1330-1400 for lunch. Alizee Diving was extremely responsive via Email but I find it that the phone works best in New Caledonia. Also, if you venture away from the town center to Nouville (Camp Est & Pointe du Nord) where there are lots of squatters, do not get out and leave your vehicle unattended. You'll be coming back to a vandalized car or even a stolen car. The squatters do not have any hesitations about starting an argument, which could turn to a phyiscal altercation. Be aware that outside of Noumea, in the south, far north and on the east coast, the beach in front of a house, even though it is separated by the main road, is still considered private property. Do not under any circumstances venture onto it w/o permission (usually is no).