The 22km of cliffs which stretch between Marseille and Cassis are fabulously conserved natural park in the heart of the French Riviera. From Cassis, you can take a boat to the hidden beaches nestled among the cliffs, or you can take the multi-hour hike to arrive at the first (and most impressive) one called En Vau. There's nothing there, no food stands, no drinks. The boat drops people off and picks them up throughout the day and passes by various beaches. They do, however, prohibit hikers during the dry season due to the risk of fires, and in that case they can only arrive by boat.