Youngsters Freya and Jackson on their holiday to climb Wyoming's Rocky Mountains. See SWNS story SWSYmountain. A British four-year-old has become the youngest person ever to reach the summit of an 11,000ft mountain - and he didn't ask 'are we there yet?' Once. Jackson Houlding, four, and sister Freya, eight, went on an out of this world summer holiday to climb Wyoming's Rocky Mountains. The pair camped in the wilderness for two weeks, using ropes to climb sheer walls that would make the most experienced hikers wince. Jackson became the youngest person to climb Pingora Peak in Wyoming's Rocky Mountains unaided - a staggering 11,889ft.