这对夫妇认为没有人知道他们在游泳池里的水下做什么，但偷窥者确实这样做了

Normally you can't see what happens underwater in the swimming pool of a nudist resort. But if the voyeur has a camera with him, he can see everything exactly. And it's incredible what people do underwater: Fucking, blowing, masturbating. And you can watch!