Even on a tight schedule, Fira to Oia Caldera Hike earns the hours.
Allow 3–4 hours one way.
The best long walk on the island: roughly three hours of near-constant caldera views, passing through the rim villages and out onto wild, quiet stretches. The catch is real exposure to sun with little shade, uneven terrain, and brutal midday heat in summer — start early or late. For walkers, the single most rewarding way to experience Santorini's geography.