The Pan-American Highway is a vast network of roads that stretches for 19,000 miles from Prudhoe Bay, on the north coast of Alaska, to Ushuaia, the world’s most southerly city. It passes through 17 countries, providing an unbroken link from the 70th parallel north to the 54th parallel south... with one exception: the Darién Gap.

So inhospitable is this 60-mile nugget of marshland and rainforest between Panama and Colombia that, even in our high-tech age of 3D printing, space tourism and undersea railways, we still haven’t built a road that connects North and South America.

To this day, no major settlements exist in the Darién Gap. Its only residents are the indigenous Embera-Wounaan and Kuna people, with an estimated 2,000 living in the area, getting around in dugout canoes. The first crossing of the gap by car in 1960 took a staggering five months, at an average speed of 200 metres per hour, and adventurers, with all their GPS and failsafes, still talk about it with the sort of reverence normally reserved for the Himalayas in winter.

“When the tarmac peters out at Yaviza, Panama, the jungle looms large ahead in the form of an endless green sea,” said Levison Wood, the British adventurer, who tackled it for his TV series Walking the Americas. “The forest, raised among the mountains, drifts high into the mist. Beyond, for over 100 miles, there is nothing but impenetrable valleys, swamps and, with disturbing frequency, death.