An explorer, in this day and age? Actually, when Hanbury-Tenison, the son of a wealthy British cavalry officer and a recent Oxford graduate, set off on his first proper adventure (driving a Land Rover from England to Burma in 1957), he seems to have been an amiable throwback: a dashing, khaki-clad sahib, a plucky, resourceful wanderer through terra incognita, in the tradition of Mungo Park, Richard Burton, and Charles Doughty. Hanbury-Tenison went on a few more thrill-seeking expeditions (including an incredible jeep ride from Recife to Lima), until 1968--when he found a focus for his energies in the Indians of the Amazon Basin who were (and are) threatened with genocide. He eventually became a co-founder of Survival International, which helps beleaguered primitive peoples around the world in much the same way that Amnesty International supports political prisoners; and thereafter he framed his journeys in the jungles of Brazil, Indonesia, and Malaysia as fact-finding missions for SI. In his later chapters Hanbury-Tenison preaches (convincingly) quite a bit on the ravages of capitalist development in the Third World, on the cultural destruction wrought by fundamentalist missionaries, on the need to set aside living space for dwindling native populations. But armchair explorers will be rewarded with many splendid accounts of derring-do--a solo trip from Manaus to Buenos Aires in a rubber dinghy, a camel ride to a Saharan oasis called Djanet, ""a thousand miles from rivers or greenery,"" etc. One only wishes that Hanbury-Tenison would tell us more about his spectacular feats of navigation: he never even mentions a compass, and it's seldom clear how he made his way through the trackless deserts and rain forests. But there's no doubt he's the genuine article, and this spirited, colorful, modest memoir shows him in a very appealing light.