Clawing for the Stars: A Solo Climber in the Highest Andes

When most altitude climbers reach their mid-forties, they slow down—but for Bob Villarreal, these years marked the beginning of his climbing career rather than the end. At forty, he took a rock-climbing class, but it wasn’t what he was looking for. In a moment of pure and life-changing serendipity, an article about climbing the Andes lit a new fire within him, and an obsession was born.

At that point, Bob retired from business and took up mountain climbing. He lost his heart to the stagger...