MT. KILIMANJARO, Tanzania—I woke in the middle of the first night gasping for breath. There was not enough oxygen in the frigid mountain air. I forced deep, steadying breaths down my throat, sure that I would wake the whole campsite. But the world slept on in the otherwise unaccustomed quiet. Neither crickets nor traffic made their home at 10,000 feet.

The next night the wind rushed fierce and unyielding across our exposed plateau. Dust blew into my nostrils, bored into my fingerprints, settled anywhere it could find purchase. Our dirty clothing hung like prayer scarves from the tent, black shorts here, white shirt there, a disarray of socks on every surface. I gazed in awe at the stars for all of five seconds before the wind drove me back inside, into the burrow of my sleeping bag where I drew two hoods around my head and let the claustrophobic security of a little nylon shell lull me to sleep.

By the third day we were high above the clouds. They stretched to the end of the earth, blocking the entire mountain from view below. The ocean of white swelled and crested in its own patterns, no less elegant for its torpidity. I half expected it to muffle sound and alter vision, but my eyes and ears perceived the world the same as ever.

Heave a breath, cough it out. One foot up, two eyes down. I coached myself up the summit two nights later, my boots sliding over the gravel and every inch of me begging for respite. A glint in the east turned out not to be the long-awaited sun but just lights from town. It was going to be a long hike.

The night passed like a dream, each minute as long as an hour but the whole ordeal compressed in my mind to a fraction of its eight-hour duration. I stood gasping at the summit with a stupid grin plastered on my face, my camera an extension of my arm as I snapped away at the monolithic glaciers and jagged craters now visible under the striking morning sun. My lungs wheezed and sputtered and berated me for making them climb above 19,000 feet with full-blown bronchitis. It was worth it.

We descended the same gravelly dunes we’d scrambled up so recently. The clouds rolled back in after a clear night; we slid down the mountain hour by hour, plunging back toward the rippling white ocean below us. It was a different world up here, harsher and quieter, isolated and exhilarating. Disorientated and deoxygenated, I imagined us swimming fathoms deep in a sky-blue ocean as ships passed above us, unaware.