You know those Zorb balls
you can get inside and roll down hills? How much bigger do you think they would have to be to make you indestructible?
There must be some cushioning between the passenger compartment and the ground due to all the air between the two, so, how big does it need to be for you to be pushed out the back of a transport plane at (say) 1000ft and bounce on the ground without injury?
See, I've never been in one but I can't imagine under what circumstances you could get injured.. They float, so being on water isn't a problem, if a truck hit you it would (probably?) bounce you out of the way...
Why don't they use these instead of parachutes? Parachutes aren't "fail-safe" and I'm sure a big ball would get you down to the ground a little quicker.