FWIW, I only have OW certification and I do at least one night dive on every trip to Cozumel, sometimes three or four, going back more than 20 years. I have never been barred from going on any dive I want to because I don't have AOW. "Advanced" is a misnomer, especially for a diver with 20 or so total dives. Maybe the cert should be called "OW2" or "OW+".I might be mistaken but I think OW can now do night dives..