[lukatmyshu]

So many questions (and so many places this could have been fixed). a) As soon your dive buddy saw your air gauge was that low he should have gone into the share air procedure. Parent's idea of letting him have your main reg while fumbling for the spare is also a good idea (although I don't believe most training includes that step). b) The divemaster should have been proactive about asking you how much air you had. It is really easy to suck down a lot of air quickly (especially your first few dives) and asking the group how much air they are using early on can indicate if someone is being aggressive with their air. c) i can't believe you guys were spread 60-70 (in total) away from each other. That's pretty far. d) If you were that low under where you ran out after 10 feet, the DM should have taken you up. Remember you also need to inflate your BCD on the surface, you don't know if the boat is going to be there, lots of things can still go wrong.

I've been in a really similar situation. 100 feet down, my dive buddy was someone who hadn't dove in 5 years. It was a drift dive and he was trying to take a lot of pictures. 20 minutes into the dive (the DM queried, he didn't volunteer) he revealed he had roughly 500 PSI left (some believe that's the level you should be at when you get out of the water). Our DM sent us up together, we shared air ... but it was still touch and go.