Well you already know my experiences DaleC from the other thread but I'll post in more detail here.
I have not had any negative comments about solo diving. On many dives I see people diving by themselves, particularly photographers. Most people I know say they solo dive occassionally and this includes people from various cultural backgrounds, not just Australians. I do not know any Northern American people locally though, perhaps it is more taboo there?
I know two people who will not solo dive and their main reasons are that they are not comfortable with it. I think this is a valid reason - some people are just not cut out to dive by themselves. I have had one argument with a buddy about solo diving, it is a long story but it involved him being left on the surface whilst two of us solo dived (was a zero viz dive to recover something). He felt responsible for us if something happened and we didn't surface. I think that is silly but I respect that he felt responsible for us and I did not want to put that on him. He is not against solo diving in concept.
The charters locally do not allow solo diving because of insurance reasons. If you get to know them they have a "don't ask, don't tell" kind of policy with solo diving. There are other things that are required by insurance that have a similar kind of policy such as when drift diving it has to be on a line and that everyone must carry a computer and a snorkel. I do not think insurance bans result from "taboos" though as drift diving off a line or diving without a dive computer or snorkel are hardly taboo (though people do debate them constantly on forums, but people argue about a lot of things in diving, solo diving is just another), and I put solo diving in the same category.
I mean, there is a Solo specialty. It can't be that taboo

And even if it was, I really do not care what others think of my diving, other than the people I am diving with as if I buddy diving, I take watching out for my buddy seriously. DaleC, I hope this does not come out too harshly but you seem to have an obsession with the idea of solo diving being taboo - it strikes me as odd as you seem to value having an independent attitude but then you seem to care a lot about what people think of solo diving. Why would you care if people at your LDS or club complain about your solo diving? The two do not add up. Perhaps you can explain it further for me
