My friends and I have made it through the game the first time, and now are going back to each world to get the star coins to unlock the areas in level 9 (the "secret" level from the princess). Our problem is that there is listed a world 6-6, but no apparent way to get to it. I don't remember if it was there the first time or not. Most of the walkthroughs I've seen so far don't mention any 6-5 or 6-6. And the two that did, don't explain how to get there, since there seems no way to do it from the main screen for world 6. Any ideas? It's the cave level in a small mountain on main screen.