Our local pool has a dedicated walking lane and it's in 1m deep water, and everyone just walks laps at their own speed.

Just this week I joined a shallow/deep water walking/running class and it was terrific. Pregnancy based but I've also seen just general ones advertised. This was at another pool, but they just closed off 2 lanes for us and we went back and forth from deep end to shallow, doing a variety of moves using noodles and foam dumbells. It was an hour long but went really quickly, very gentle but my body did get a decent workout. Good luck with finding what works for you!