I know of a few incidents of attempted voyeurism and one of actual voyeurism of a woman (that went to court) in a local pool. The attempted ones involved School Sen children; luckily enough staff to be aware and stand to create barriers and pool staff also monitored.
Separate rooms are available for sex segregation of pupils, but not anywhere near enough which meant girls (as there are always fewer) had to go in public cubicles over seen by staff and the nature of some pupils means they need to be on their own (usually with one adult overseeing them, or even two). This is difficult and stressful for staff at times. Staff also swim with the children and need to get changed.
The only pools around here where it's worked well are the sex segregated ones.
The voyeur was not convicted due to lack of evidence but recently has been due to other related offences he went on to commit.
Staff on swimming trips constantly watch for suspicious men. in the past, the main one I'm thinking of was spotted timing their swims with a class, including entering the shared shower area and then changing village at the same time.