Around nine kilometres west of Marseille lie the dyke-linked limestone islands of Ratonneau and Pomègues, known jointly as the the Îles du Frioul. Seabirds and rare plants thrive on these tiny outcrops, which measure around 200 hectares combined.The remains of old fortifications and quarantine stations add interest, and the islands offer excellent rambling. Frioul If Express boats to Château d’If also serve the Îles du Frioul (one/two islands return €11/16, 35 minutes, up to 21 daily).