I did the blue hole in Belize too! Very nice. I was at 140+ on air which was deep enough to get to the huge stalactites. Besides there wasn't a lot past there to see. We stayed down 8 minutes I think. I have been to max 170 on air on another dive but for just a very short time..a minute or so. There wasn't much to see there anyway. Unless you're going to get a look at a shark or something else down there of interest it aint really worth going down there. Less to see and you shorten your dive time and your dive com will nag you a lot on the next dives if you don't have one made for deco diving.