Reaching the summit of Mount Everest in 1953 is widely considered as one of the greatest achievements of human endeavour.
But budding explorers 60 years on are faced with a far shorter list of possible achievements, and few firsts left to conquer, according to a modern-day "adventurer".
Ed Stafford's comments come on the 60th anniversary of Sir Edmund Hillary's successful expedition on May 29, 1953, when he and Tenzing Norgay became the first men to reach the 29,028ft (8848 metres) summit.
Since then, an array of conquests have been achieved, from putting a man on the moon to Hollywood director James Cameron's solo descent to the deepest place in the ocean last year.
Among the array of extraordinary achievements, the conquest of Everest remains one of the best-known "firsts" in the world of exploration and adventure, but Mr Stafford today said the list is rapidly dwindling.
In 2010 the 37-year-old became the first person to walk the length of the Amazon River in an epic expedition that took two-and-a-half years.
"It was something that everybody said was impossible but I decided that I didn't think it was and so set out to do that," the former British army captain said.
"It took two and a half years, I got a Guinness World record for doing it, no-one's ever done it since so that's my foot in the door in the world of exploration.
"I think the amount of things that there are left to do are certainly slimming down now.
"Increasingly people are just looking to beat other people's times or do it faster or do it with less kit or whatever.
"I think things like Everest are in a group of their own now and we will be in a period where there is less and less world firsts."
"The world is mapped now, we've got Google Earth and things like that so we aren't writing maps, we aren't exploring in that sense at all.
"But that doesn't mean that there aren't feats of endurance or feats of human endeavour that haven't been done before that when they're done are very impressive."
He said the modern-day equivalent of Everest would be to go around the world via both poles, but with no vehicles or help.
He added: "That's something that no-one has ever done before.
"People have circumnavigated the world, people have done it via both poles, Sir Ranulph Fiennes, but using Ski-Doos and motor-powered vehicles and things like that.
"It's never been done man-powered and I think you have to extract certain things that make things easier in order to find something that's pure enough to count as a world first."