Higher

A U.S. Air Force pilot looked down at the suspected Chinese surveillance balloon as it hovered over the Central Continental United States February 3, 2023. Recovery efforts began shortly after the balloon was downed. (Photo courtesy of the Department of Defense)

Pretty cool. Airliners fly at 40,000 feet. The U2 can get up to 70,000 feet. This balloon was at 60,000 feet. Balloons can get higher. Remember Felix, the balloon jumper? That was from 127,000 feet.

I'm reading Into Thin Air by Jon Krakauer about the 1996 Mt. Everest climbing disaster. Mt. Everest is 29,000 feet tall. Base camp, starting point for most every climging expedition, is at 15,000 feet. The FAA (Federal Aviation Administration) requires pilots to have supplemental oxygen if they are flying over 12,000 feet. I've been up to around 10,000 feet while hiking and I got to tell you there's no air up there.

Via My Daily Kona

P.S. Neil deGrasse Tyson tells us that the tallest mountain, measured from the Earthś center is not Mt. Everest, but Mt. Chimborazo in South America:

Neil deGrasse Tyson - the tallest mountain relative to Earth's center
It's not rocket science

Tallest Mountains in South America

Turns out that eight of the ten tallest mountains, as measured from the center of the Earth, are all in South America within a few degrees of the equator.