The Sims 2: Castaway

If u have gotten 2 the 3rd island go to geyser springs im not sure if thats what it is called then theres an old stone door and keep inspecting and all of a sudden the door will open go through there and keep following the path and you will go to the other side
hope it helps

Im not to sure if you just find a column or tree hanging above the quicksand and use a rope on it

****How to Cross the Quicksand****

First off, if you have the Crown that you found in the Acient Temple behind the throne on the floor. Take and go into the DArk Cave and use it to open the new area.

Cross the water and head straight back to where there are floating footprints that will say "explore East River Plains''. If your Sim is maxed on all moods; then go explore this area.

It will lead you to a path where there is 2 Pillars and the Quicksand. inspect the Pillars by walking around it or up to it till it says Inspect. Click on it and your Sim will Push the Stone Pillar over. Now you can walk across the newly Stone path and across the quicksand.

****Charisma - How to get it. *****

Charisma is a skill that is built up by talking to the Monkies, your other Sim.
Or when you build a Sand Buddy and interact with it.

Hope this helps.
Have a good day!

Ark!
You need to go to the Llama Temple 1st!@
Then go find the crown, and go back.
On the 3rd island, you go back to the 2nd island and go to the dark cave
1ST you go straight to the Dark Cave(Deep in the dark cave there is a door wich can be only opened if u had the Llama King's crown).
2nd it opened.
3rd get in(dont walk. interact with the door)
4th Volla! you got yourself at a beautifull background.Go Straight and you got yourself at the (West or East) River Plains and you found a treasuer map piece.
5th there's a broken statue, you interact with it and choose "Inspect" and then the statue will fall and create a bridge.
Or use cheat