In July of 1981 I was invited to participate in the Santa Cruz Trek in the Cordillera Blanca with a group of young Israeli people, a nurse, a medicine student, a dancer, a man from a Kibbutz, a housewife, a Teimani who had just finished his army service... That was the experience of a lifetime. This is at lake Icchi Cocha, we had acclimatized already for a few days.
We went up to over 4,000 m!