I am amused reading these posts about mixed swimming and then talking about 100-125 years ago.
Our family was in the clothing business, both manufacturing and retailing from 1890-1995.
Bathing attire 100 years ago was more tznius than average non-frum street clothing of the past 60 years.
There were no exposed midriffs, both men and women wore full tops, no short, shorts and the bathing costumes were a dark heavy material, ladies in long sleeves.