Left is the correct way to go. Going right will lead you to the dead end island. Though there is another fork in the road which is slightly hard to see. On your way up the circles (after you turn left at the first fork), you will see another path leading down. It is slightly hard to see, but when you find it, go down that path and it will lead you to the top. On what Warrior4ever has said, it is best to plan your routes using the F3 mode camera to find which way leads to where.