Someone posted about this on the EA forums:
http://forum.thesims3.com/jforum/posts/list/129886.page#1588059If you have the Tears of Horus adventure reward from the special merchant in Egypt, you can see the dig site and relics to the southeast of the little island in France. You need Pangu's Axe from China to break the big boulders covering a stairwell. This goes into an elaborate tomb and at the very bottom you will find a green dive well to get to the island in France. You need two Sims to get through the puzzles here, or you need to have found the pieces for and reconstructed a pushable statue beforehand. On the little island, there is a room with life fruit plants, money trees, all the rare grape varieties, and even death flowers. I had my Sims harvest these and that's where they got the produce to plant their own life plants and death flower bushes.
If you have a vacation home in France, you can also get the teleportation pad lifetime reward and put it in your home. Then all of your Sims can teleport to the little island directly and use their cell phones to teleport home.
My Sims love France, as I think it has the fewest adventures of the 3 locations, so they finished them and can now go there to focus on their skills and skill challenges (mostly nectar making and writing books). When they get stressed out they can go for jogs in the countryside and jog home. They even got extra sets of martial arts training dummies and blocks from China for their French vacation home.