Anyone here know about skydiving?

[Hoser]

I'm probably wrong here, but I thought you had to have oxygen to go above 12,500?

It has been 13+ years since I did any HALO, but...

Depends on the Military or civilian side of the house and how long you are above 12,500 ect.

In a nutshell (civilian) above 15K everyone must be on the hose. Military, crew must be on O2 above 10K and jumpers above 13K.

Above 18K you must prebreathe O2 for 30 minues before depressurizing.

And tons more rules like it.