Altitude sickness affects everyone differently, the experience for me felt much like a sadist was trying to scoop out the right side of my brain with a rusty spoon. I sat, winded, on the side of the path as the lucky unaffected gleefully trotted by, somehow oblivious to the 5,000 meters we were above sea level. The danger of altitude sickness is like the danger of a riptide- invisible, persistently underestimated, subtlety lethal. Thinking about it, the glacier trek we were on actually couldn't have been a better introduction to the dangers of altitude. We were in a highly controlled environment (multiple guides, well stocked on water and medication, a physically easy and flat trek, a large group) and were therefore never in danger of becoming disorientated or lost. We simply tasted a small appetizer of what can happen at altitude and learned to be over-prepared when hiking up high.