Exactly how steamy is this story?
PG
The Lost City of Z is about as steamy as flipping through an old issue of National Geographic. Sure, you might encounter a few naked people here and there, but that's how they live their lives. It isn't sexual in nature. If you lived in an environment with temperatures over 100 degrees every day, you'd be naked, too. Although the bugs might prompt you to cover up a bit.
There are some photographs in the middle of Lost City of Z, but again, this isn't a centerfold. The pictures are there to illustrate, literally, what the people of the Amazon look like. Surprise: they look like people.