I use G4 Dexcom.
Spent almost an hour in swimming pool last year on holiday. Sensor was under water 90% of the time I guess.
Sensor , once I was back in range, continued to read with no problems.
I did put a new patch on prior to going swimming. Old patch had been on for over a week and I didn’t want to take any chances.
Swam in the sea in the Maldives for over an hour at a time with Dexcom G6. The adhesive started to peel a little, but with a bit of rock tape I got 14 days out of it, which wasn't too bad.