Bring plenty of water and sunscreen. To get to the green sand beach from the parking lot there are locals that will drive you there for a fee. If you decide to walk there are no signs to direct you which way to go.
We stayed on the dirt path and looked for the vehicle that were transporting people to the beach.
one of the stranger things to do in paris .. and not a top 10 item for paris sights, but i really wanted to see it, and im glad i did! it was interesting to learn the history of the sewers .. and if you are a Les Mis fan, there are lots of interesting tidbits abt scenes in the book.