The Frioul archipelago — four small limestone islands a couple of kilometres off the coast — sits within sight of the city and is the obvious half-day escape from Marseille. Most visitors come for the two larger islands, Ratonneau and Pomègues, linked by a man-made dyke and home to a small marina, a sleepy fishing village, scrubby walking trails and several swimming coves with clear water. The third island is the Château d'If; the fourth, Tiboulen, is uninhabited.
Boats run year-round from the Quai des Belges at the Vieux-Port, often combined with a stop at Château d'If. Bring water, swim shoes for the rocky beaches, and a packed lunch unless you want to eat at the harbour-front restaurants on Ratonneau. The walking trails take in old quarantine hospitals and gun emplacements left over from successive wars. Crowds peak in July and August; April, May, June and September are far better for a quieter visit.