I’m looking for an older foreign film (I think it’s French) where there’s this family living in the woods, and this teenaged girl with short, shoulder length hair is walking around (I think the whole movie) in her blue, one-piece bathing suit.

She has younger siblings (I think) and the film takes place in the family’s home in the woods.

Anyone know the name of this particular film?? (I saw part of it on a weekend when I was a kid and it stuck with me. I REALLY wanna see it again.)