Perissa Black-Sand Beach is a real time commitment — fit it in only if it's a priority.
Allow Half-day.
This is Santorini's beach-day done properly: dark dramatic sand, clear water, loungers and food all along the strip, and a relaxed, social vibe. The catch is that black sand gets blisteringly hot underfoot by midday and the beach is wide and built-up rather than secluded. Great for actually swimming and lounging, which the caldera side can't offer.