Sulani Island Festivals - When Do They Happen?

Of all the silly things we get notifications for - you would think we would get notifications for island events or they would be on the calendar. I have finally seen a few but only after my sim moved to the island they are on. The fishing one is in the cove. Others are in that festival area - they are no big deal though - just some sims around a bonfire that are usually not even the regular sims that live there. I have yet to see the sand castle contest one.