I am currently reading, "Up the Creek; An Amazon Adventure", by John Harrison (1986).
From the back cover; "A hazardous and gruelling Amazonian journey recounted with humour, disarming honesty and gusto. John Harrison's quest to reach the upper limit of the Jari River in Brazil and portage his canoe across the mountains into French Guiana is ambitious, flawed and just a little bit insane. But the trip itself, full of unexpected encounters, crippling bouts of malaria, moments of intense emotion and hours of crushing boredom, is as inspiring as the tales of the earliest adventurers."