Santorini and Mykonos, the most popular Greek Islands in the Cyclades, are less than 100 miles apart. The idea of island hopping between them seems like a no-brainer and, in some ways it is. But it's not something you can do on impulse, the way you might ask a local boatman to take you to a secluded beach. You need to plan ahead to make sure you have enough cash - and time - to do it.
Can You Make It a Day Trip?
Probably not. Whether you fly or take a fast boat, it takes two or three hours each way. Factor in landing, getting your bearings and arranging local transportation, and you won't have much time left for local exploring. And, you will probably not return on the same vessel you traveled out on. With the exception of the tiny, rarely visited island of Anafi, Santorini is the southernmost island of the Cyclades group and furthest from Athens. So, essentially, it is the end of the line on most ferry routes. Boats traveling between Santorini and Mykonos don't go back and forth between them. The islands are ferry stops along the route of longer voyages.
On the other hand, the two islands make reasonable partners for a longer vacation or as part of an island hopping itinerary. These are the main ways to travel between them.
Several companies run high speed ferries and jet boats between the islands during the popular tourist season. Tickets are available from travel and ticketing agents on the islands. And new in 2019, some of the ferry companies have made booking online much easier, are offering E-tickets and even have Apps.
Sea Jets operates fast boats from both the old port and the new port at Athinios on Santorini. Depending upon the boat, the trip takes from just over two hours to just under three and, in 2019, costs between €43 to €66.80 each way. For the most up-to-date information and accurate fares, enter your chosen departure in the booking widget on their website. And make sure to read the site's FAQ to determine how to get your ticket.
Golden Star run their "SuperFerry" high speed ferry and SuperCat catamarans between the islands from the end of May until the beginning of October with at least three sailings a day in each direction. The trip by ferry takes between three hours and 30 minutes and four hours (depending on the direction), while the SuperCat voyage lasts about two hours and 50 minutes. The cost is between €42 and €52 depending on the direction and the boat. Their website shows that prices are "indicative", which like the British Parliaments "Indicative" votes in the Spring of 2019, means that they are not guaranteed.
As of May 2019, Hellenic Seaways are not offering any routes between Mykonos and Santorini. This could, of course, change in the future.
Flights between Santorini and Mykonos take between 1hour 50 minutes and 2hours 30 minutes, including an obligatory 30 minutes on the ground in Athens. That's right, every scheduled flight between the two islands involves flying to Athens and usually changing planes. To put that into context, it's a bit like flights from New York to Philadelphia having a stopover in Boston.
Aegean Air, in partnership with Olympic, flies this route, with one way fares in the summer of 2019 averaging €82 but starting as low as €51 and rising to more than €200, depending upon the day of the week and the amount of lead time before your chosen flight. The Greek domestic airline Sky Express is no longer showing any flights - direct or connecting - between these locations.
Deep Pocket Fantasies
Both Santorini and Mykonos have airports and, if money is no object, there are air taxi services that can be booked to travel between them. Helicopter fares start at about €3,000 for a 30 to 40 minute flight for up to six passengers. Or, you could always book a Lear Jet starting at €5,750. The Greek Air Taxi Network is the first stop for finding private operators and booking your fantasy flight.