At SAB, they are checking ID's at every entrance from about 9:00 a.m. to about 7:00 p.m. If you are staying at the Yacht Club, Beach Club or Beach Club Villas, you will be allowed in and are given an orange wrist band. (My daughters wear the wrist band around their ankle and no one seems to mind). I came a few minutes after my wife, who had the room key, and was not allowed in until my wife came over to rescue me. I also tried to enter without an ID, while fully clothed and without bathing suit, but was refused entrance. You will not be allowed in to SAB without a Yacht Club, Beach Club or Beach Club Villas room key. I wore the orange wrist band in the water for several hours yesterday and I did not notice it on my arm.
As for the quiet pool, it is unsupervised. Anyone can enter and use it. There is seldom more than eight people in the quiet pool. The hours are 7:00 a.m. to midnight, but last night I noticed six young adults (twenty-somethings) who were in the quiet pool at about 1:30 a.m.
We've been here for 7 days now and I still love this resort.