Ah, but there is the rub. Entering one place and exiting another is much more possible to happen penetrating a wreck than in a cave. Of course that probably means that something went wrong and the dive plan wasn't followed, but still...
I still like the "keep your gas with you" option when wreck diving, but I'm not doing the degree of penetration on them that some of you are either.
On wreck diving you have to make the decision on your penetration:
1. Continuous line in and out.
2. Progressive Penetration - no line.
If # 1 then you can leave the bottles because you ARE coming back the way you went in. (and spooling up your line)
If # 2 then you do not leave your bottles because you expect to exit from another point.
(not to be meant to validate to the merits of either method)
Cheers
JDS