At the end young native boys and girls leave in a boat all naked. Private areas and bare butts are shown.
Many native women are shown topless. Bare breasts and nipples is shown completely.
The South American tribe doesn't wear much. The adult men and women typically wear only loincloths, so there are quite a few shots of topless nudity. The men's loincloths don't cover up much in the back. While quite a bit of nudity is present, it's all portrayed naturally rather than erotically; its simply the way the primitive tribe dresses.
Young boys are seen completely naked throughout the movie walking and working. A young girl is shown briefly naked at the end walking. None is sexual.
A man and woman are found lying in bed next to each other naked and he kisses her; they're facedown so anything critical is covered, though quite a bit of cleavage is shown.