After centuries of exploration - and with more than a little help from satellites - the earth's surface has been fully mapped out. So what's left to explore? Plenty, says Nick Smith.
If you talk to any professional mapmaker today, you will be told that we now know where everything is. End of story. Advances in satellite mapping mean there are no surprises remaining on what geographers call the 'surface topography'. Gone are the days when our cartographic forebears would decorate the blanks in their atlases with illustrations of three-headed sea serpents or dragons. One of the greatest minds of Ancient Greece, Ptolemy decorated his atlas with elephants, hippos and cannibals.
The Okavango Delta
Nearly two millennia later, there may no longer be any remaining 'gaps on the map'. But that doesn't mean we're much closer to becoming experts on the more far-flung regions. We should resist the temptation to suppose that the moon might hold the record for being the least explored place in our (somewhat) immediate environment. While it is true that only 12 humans have ever set foot on the lunar surface, a paltry three have travelled to the deepest point of the earth's oceans - Challenger Deep at the bottom of the Mariana Trench.
A century ago we knew virtually nothing about the interior of Africa and even less about mainland Antarctica. No one had officially set foot at the North Pole, and Everest was still a dream. Today, these landmarks may well have been achieved, but that doesn't mean you can't still find isolation on our overcrowded planet. Deep in the heart of northern Botswana is the largely uninhabited Okavango Delta, covering an area around the size of Wales. The 'swamp', as it is known, is one of the last great wildernesses on earth. But when it comes to size, swamps are nothing compared with deserts. The world's largest hot desert, the Sahara, and the largest polar desert, Antarctica, cover more than 9 million square miles between them. Both are strewn with the bodies of lost explorers.
It's tempting to think of 'remoteness' as a vague statement about something far away. But geographers can now measure it, having come up with the concept of 'poles of inaccessibility'. While 90° south has fascinated explorers for centuries, it's technically not the most remote place in Antarctica. Calculated as the point on land furthest from the sea, the honour goes to a co-ordinate on the map that reads approximately 82°S 54°E. It is an extraordinarily difficult place to get to, and should you ever find yourself there, you'll be able to dust the snow off a bust of Lenin left behind by an intrepid band of Soviet explorers in the late 1950s. There are poles of inaccessibility all over the place. In Eurasia, it can be found on the Kazakhstan border with China, while in South America, you'll need to travel deep into Brazil to find it, just outside the small town of Arenápolis. The most remote place in Africa is near the seldom-visited tripoint where the Central African Republic, South Sudan and the Democratic Republic of the Congo meet.
In nature, it seems that explorers might have even more to learn. Despite having discovered and named around two million species, scientists think this might be only a quarter of what is actually out there. Admittedly, most of the other six million species are probably tiny insects - there will be very few as-yet-undiscovered species of megafauna out there - but it does raise the enticing possibility that somewhere, in the more remote corners of the planet, there really may yet be dragons.
Nick Smith is an editor on the Explorers Journal and a Fellow of the Explorers Club and the Royal Geographical Society.