Please refer to the PADI open water book, in there you will find the following statement or something similar to it. Diving within recreational depths and within NDL you can always complete and Emergency Free Swimming Ascent. Now that means you must still ascend at a controlled although accelerated pace and "vent" the expanding air as you go. I understand that PADI no longer recommends practicing this in the classes, but when I did my class we all performed a Emergency Ascent from 60' with no problems. Now all of us decsended and started the manuever so we had esentially no Nitrogen in us, and personnally I was very surprised how quickly I had to "vent" air on the way and how far the air really.