Strictly Orthodox women are reportedly preparing to “take action” against the decision to open the Hampstead Heath Ladies Pond to transgender swimmers, which means they cannot, under Jewish law, swim there.
Under halacha, no one can change their gender, and so trans women would not be considered women.
While Jewish law permits Strictly Orthodox Jewish women to be in a state of undress in front of other women, it is forbidden in front of men.
https://www.bbc.com/news/uk-england-london-48380940