There are no nudity or obvious sex scenes shown in this movie.
Her uncle climbs in bed with Mackenzie, pulls back the covers, exposes her underwear and stomach, and is implied to molest her. He climbs in her bed several more times. Nothing explicit is ever shown, but it's disturbing.
Mackenzie takes a shower in a stranger's hotel room (teenager's) and then comes out in just a towel. She hangs out in his room for a while, takes a nap, and eventually kisses him. No sex or nudity. Nothing sexual at all.
Mackenzie removes her shirt while Bartlett is sleeping next to her in a tent. She tries to kiss him. However, he interrupts and stops her immediately. She is implied to be naked to the waist.