"For millennia the location of the Nile River’s headwaters was shrouded in mystery. In the 19th century, there was a frenzy of interest in ancient Egypt. At the same time, European powers sent off waves of explorations intended to map the unknown corners of the globe – and extend their colonial empires. Richard Burton and John Hanning Speke were sent by the Royal Geographical Society to claim the prize for England. Burton spoke twenty-nine...

"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. After his humiliating election defeat in 1912, Theodore 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 de Silva Rondon, Roosevelt...