thanks PoolDoc for the further info.

At this point, I will have to assume that delamination is indeed the problem (fingers crossed it's not something more serious). I guess the most amazing thing about this is that i had no idea that solid plaster could develop these types of floaty areas, almost bubble-like or squishy areas. In my mind, plaster is like concrete, but obviously it can "move" in a sense, or has some type of flexibility once water has encroached and there's been a separation between plaster and gunite. As far as patching it goes, I have heard that some patching can be done underwater without draining so that's probably what I would go for (least expensive option when finally necessary), mainly because homes out here aren't worth the money to pump a lot of $$ into them due to the housing crisis. At sale, I'd never get my money back out of it, so everyone in Vegas tends to approach repairs this way unfortunately.

Anyway, THANK YOU so much, your help is truly appreciated and I will be sure to visit pool forum for my future pool advice and needs.