Carstensz Pyramid - Acclimatisation From a medical perspective, we are climbing at very high altitude (up to 4,884m). At sea level, the standard barometric pressure is 101 kPa. At 4,884m on the summit of Carstensz Pyramid, the standard barometric pressure is 57 kPa. This lower oxygen pressure means that there are fewer oxygen molecules in the same volume of air - there is only 56% of the oxygen available compared to sea level. Your body reacts to this lower oxygen level in a variety of ways - for example, your respiration (breathing) rate increases, and your body starts to generate more red blood cells. The respiration increase begins immediately, but the production of extra red blood cells takes longer. Due to the use of helicopters to make rapid access to Yellow Valley Base Camp at 4,300m, we are unable to follow a typical climb high / sleep low profile. The team will take Diamox (Acetazolamide) prophylactically (starting in Timika) to speed up the acclimatisation process.