My first night dive was about dive #15 or so, part of my AOW class. I was a little apprehensive about it, because a friend had told me she had had to abort her first night dive from a claustrophobia/anxiety type reaction. But we actually went into the water before it was full dark, and that made the beginning of the dive easy. And I was buddied with my favorite instructor, which helped, too.
I actually didn't find it to be all that much different -- but of course, almost all the diving I had done to date was in pretty darned poor visibility. Whether you can't see something three feet away because it's green or because it's black doesn't make a great deal of difference
The only thing that bothered me was when we would meet up with some of the other divers that were down with us, and then I had a hard time keeping track of which diver was my buddy . . . but I've had that problem since in the daytime, too.
The site we dove isn't one which is noted for a lot of "wildlife", but we did see some ratfish, sturgeon poachers and at the end, a beautiful little skate.
The funny thing was that, when we came out, we were talking about people tending to use more air at night because of the little bit of anxiety that the dark causes. My instructor said, "Oh, I used much LESS air on the night dive." When asked why he thought that was so, he said, "Well, I could either see Lynne's light or kick her, and either way, I knew where she was." I guess Bob and I had similar ways of coping with night diving
It was a good experience, and I would have no hesitation about diving at night again (in the right places, with the right people, as always!).