How long time in advance do I have to arrive in Cusco before hiking?
The high altitude of this region means that at 9900ft(3000m) the atmospheric pressure is only about two-thirds that at sea level, and at 17160ft(5200m) it is only about half. This reduced pressure causes problems for visitors, who may suffer from altitude sickness. Acclimatization takes a few days, so PACHA recommends that you get to high altitude at least two days before you start your hike. Hiking in high altitude is not recommended for those who suffer from weak hearts or lung complaints.