3 Best Sights in Side Trip from Cannes: Îles de Lerins, The French Riviera

From the drop-off point on Île Ste-Marguerite, walk left for 10 minutes to see the Fort Royal. Built by Richelieu and improved by Vauban, the fort offers views over the ramparts to the rocky island coast and the open sea. On the southern side of the island, you'll have to get wet to see the underwater eco-museum: its six statues are submerged 92 to 144 yards from the shore at a depth of 10 to 16 feet. The island's two restaurants—L'Escale and La Guérite—are both closed from mid-October to spring. They're also rather pricey, and the service is not as good as the fish; you are paying for food with a view. Public toilets are accessible. 

Smaller and wilder than Ste-Marguerite, Île St-Honorat is home to an active monastery and the ruins of its 11th-century predecessor. The monks are more famous in the region for their nonreligious activity: manufacturing and selling a rather strong liqueur called Lérina. Retreats at the abbey's hôtellerie require a two-night minimum stay, and you must bring your own sheets and towels and obey the rule of silence (even during mealtime). There is no cost, but a donation of €45–€55 per night per person is welcome. There is Wi-Fi but only in a restricted area. There are no garbage cans on Île St-Honorat, so be prepared to take any trash you generate back with you to Cannes.

This complex is famous for reputedly being the prison of the Man in the Iron Mask. Inside, you can see his cell and hear his story. The truth of his captivity is not certain; however, it is true that many Huguenots were confined here during Louis XIV's religious scourges. You'll also find a Roman boat dating from the 1st century BC and a collection of amphorae and pottery recovered from ancient shipwrecks.