My son and I are returning from a trekking in the Sierra Nevada National Park and there have been many experiences in the heights to describe them in a small text, so I will try to make the photos describe the adventure better than my words.
One key is to acclimatize the body to the altitude, so the first night we slept in Pradollano and almost at sunset we went up to 2700 m
The other two nights we slept above 3000 m, one of them under a sky full of stars at the foot of the Mulhacen, the other in a refuge. Up there only reigns the sometimes very strong wind, the rocks and the alpine goats, also tiny flowers and lagoons of glacial origin.
Something unites the people who walk the high peaks that pushes us to help or be helped, being up there is like walking on another planet where the rules are not set by us but by the mountain itself.