Hellymart, how horrible for you. Quick thinking to cover the shoe with a towel. I don’t think that our local swimming pool has gaps like that in the unisex cubicles, next time I’m there, I’ll check.
Many, MANY years ago (50+) a friend was terribly upset when her brother drilled a hole in the bathroom wall from his bedroom. He wanted to see what women looked like in the nude! Her parents quickly took action, but my friend was very upset afterwards. Nowadays, with small cameras, etc, the consequences can be longer lasting.
Don’t let this put you off swimming, and well done on your quick thinking ?