John Harrison is a Bristol-based explorer who has made a number of canoe expeditions to the Amazon, always travelling with only one companion and with no radio or back up if things should go wrong. Two of these expeditions have lasted more than 6 months. John has written two books, "Off the Map: The Call of the Amazonian Wild" (2001) and "Up the Creek: An Amazon Adventure" (1986). He has been the subject of a National Geographic Film and has broadcast for BBC radio. In addition to his canoe exploits in Amazonia, he has also canoed extensively in N.America, Europe and Africa.