Here is an update.
I went diving yesterday. Because my period seems to be irregular starting anywhere from 3 to 4 weeks since the last one I am expecting it to start any time now. I haven't really had any symptoms that usually let me know my period is on it's way but just to avoid any surprises especially because I was going to be at a site with no facilities I opted to wear my Diva Cup.
I had no problems with it what-so-ever. It is usually very comfortable for me and I don't feel it when in place; I did not feel it yesterday. Although I did not do a deep dive by any means (max depth = 21') all went well. I did not feel it, nor did I have any issues with 'pressure'. I was not able to remove my cup right after the dive and as the day progressed there really wasn't a good time for me to remove my cup to check for water that might have seeped in it ( I simply comment about that now as I know some other users have questioned the possibility of water getting in the cup while swimming, bathing, or using a jot tub). I have to admit I didn't expect water to get up there and it never really worried me. When I got home, I removed my cup and there was no water what-so-ever in it.
I fully intend to continue to wear my menstrual cup when diving whether I am on my period or expecting it and wanting to avoid a surprise! If on my period though I will try to empty it before the dive jwhenever possible just to help avoid possible leaks but, if I can't, I really won't worry as wearing the cup I have no doubt will be better that the experience I have had with tampons.