Peter Fleming, the brother of James Bond creator Ian, and reputedly an inspiration for his more famous sibling's iconic character, was a traveller, explorer, and very talented writer in his own right. Brazilian Adventure is his thrilling, hilarious account of a peculiarly pointless expedition into the jungles of South America in the 1930s. If you enjoy real-life adventure stories dating from times when men really were men and our world wasn't yet fully explored, you'll love this. In my view, it is a far more rewarding read than any of his brother's books.
Peter's books describing his travels in the Far East, entitled One's Company and News from Tartary, are just as good, and worth seeking out. Also worth a look if you enjoy this kind of thing is Julian Duguid's obscure Green Hell, which tells an almost identical story to Fleming's Brazilian Adventure, and if anything, is an even better read.