and if we assume a regular swimming pool of 1,25m depth then that's not risky endeavour, with air (12l @ 200bar) lasting way over an hour even under intense action.
Even the most graciously dimensioned swimming pool (assuming 5m depth) would not be much of a problem, tho pools deeper than 3,5m are hard to find.
I do know a location that has a ~10m deep pool but they only allow certified divers in, so not really an option.
https://www.monte-mare.de/rheinbach/tauchen