J.P.
They are everywhere, aren't they. My niece's swim class ended up with one of the boys on the bottom of the hottub after class- had to call 911, do cpr, because the mom was busy chatting away at the other end of the place. He ended up being fine.
Do the owners not know who the mother is? I would either talk to the management, or when the girl is told not to climb, let that instructor know that the mom is "over there" on the phone, or whatever. I didn't leave my 18 month old unsupervised at home, nevermind at a gym!!
BTW, I also cloth diaper, and love to share, so feel free to ask me any questions. :)