Around 16 minutes into Martha Marcy May Marlene. Elizabeth Olsen, younger sister of Mary-Kate and Ashley Olsen, strips nude to go skinny dipping. We see Elizabeth’s ass as she strips and dives into the lake. We may be able to see Elizabeth’s breasts and bush as she swims but it was hard to tell as the water was obscuring the view.
20 minutes in, we see a bunch of female cult members in various states of undress as they change.
At 26 minutes, Elizabeth shows her right breast as she changes.
About 37 minutes in, we see a female cult member dive off a cliff. Then we see more cult members skinny dipping underwater.
And finally at 67 minutes, we see an orgy scene with some cult members. Elizabeth is shown topless on top of a guy. I don’t think any of the other cult members showed anything.