For each port, Celestyal offered paid shore excursions. We didn't buy any, but got a promotional deal that included two. Mykonos was not one of those. If you didn't go on a shore excursion, generally you were left on your own to figure out how to get from port to whatever you wanted to see. Mykonos was the exception: Celestyal did provide these complimentary buses to get from the new cruise port (way far away from everything) to the old port, near town.