If you are looking for a book to read on a trek, I would highly recommend Candice Millard's The River of Doubt. It's about Teddy Roosevelt's trip down the amazon after he lost his bid for the presidency on the Bull Moose ticket. An awesome account of an awesome man. After his humiliating election defeat in 1912, Roosevelt set his sights on the most punishing physical challenge he could find, the first descent of an unmapped, rapids-choked tributary of the Amazon. Together with his son Kermit and Brazil’s most famous explorer, Cândido Mariano da Silva Rondon, Roosevelt accomplished a feat so great that many at the time refused to believe it. In the process, he changed the map of the western hemisphere forever.The River of Doubt—it is a black, uncharted tributary of the Amazon that snakes through one of the most treacherous jungles in the world. Indians armed with poison-tipped arrows haunt its shadows; piranhas glide through its waters; boulder-strewn rapids turn the river into a roiling cauldron.