Lima by the coast is about an hour's flight to Cusco, which is at 12,000 feet elevation. At this elevation, Rose and I experienced altitude sickness despite taking pills to prevent it. In fact, the symptoms were the same when one took the pills. Coming down from Peru to Lima is even worse. This is what happened to the half empty water bottle I had when the plane descended from 12,000 feet down to sea level in one hour. Imagine what our body went through during that flight.