While several climbers have achieved this feat before, none have ever done so without using bottled oxygen and without descending to the Everest base camp.

Setting off from Camp IV at 6 a.m. on May 21, it took the 45-year-old almost nine hours to reach the summit of Lhotse (8,516 m above sea level). Returning to Camp IV, he then set off up Everest (8,848 m above sea level) following a short rest and a meal.

After taking 14 hours to reach the peak of the world’s highest mountain, he then began his descent back to camp. According to one mountaineering tracking portal, Krzyżowski is in good shape and currently on his way to Everest base camp.

A lawyer by profession, Krzyżowski also works as a volunteer in a GOPR mountain search-and-rescue group. First gaining experience climbing in the Tatra Mountains, he has now conquered seven ‘eight-thousander’ mountains without the aid of bottled oxygen.