The Lerins Islands are close to Cannes and you may visit them by using one of the boats in the Port (west of the Palace and Hotel de Ville). The cost of round trip to Margarieta Island is ca 22 euro, to St, Honorat island it is 28 euro return per person.
It makes a great trip away from cannes with the good half day time - if you like more "filled in" my advise to use margarita island, while St, Honorat - it is great island to be with yourself, have a walk and think over some eternal topics - it is in fact owned bz the monastery so there is no picknick or game places, just a networks of pather around and some old ruines and monastery fort (to wait out the sea attacks in the mid ages time) - with the great view of the monastery and Esterel massif to the west.
You may visit the mass there and also buy some staff (wine made on the island - rather costly but rare and well deserved the price). But I think the most of the St. Honorat - it is solitute of the sea and nature, calm just a mile away from the vibrant Cannes Croisette!
Well recomended to make a trip to one of the island or both to experience the famous city from different point of view.
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