How Do I Get to Santorini?
Take a Flight
Take a flight from the United States to pretty much any city in Europe as there are currently no direct flights from the United States to Santorini. If you are trying to save money, fly into the city with the cheapest airfare, which usually is either London or Dublin. If you want to save more money fly out of a major city in the US, such as NYC. You can then book a ticket to Athens on one of the budget airlines in Europe, such as easyJet or Ryanair. During peak season, some flights fly directly to Santorini from London Gatwick Airport so you would not need to go to Athens first.
If You Get to Athens, and Don't Want to Fly to Santorini, Take the Ferry
The Pireas Ferry Terminal is about 1hr 15min from Athens International Airport
You will have to find transportation to the port of Pireaus, which is just over an hour from the Athens airport. Once you're in Pireaus, you can buy your ferry ticket at the port. Three different ferries can take you to Santorini. Ferry rides take 5 to 10 hours to arrive and prices range.
Take a Flight, Then a Train, Then a Ferry (or a Flight)
Once you're in Europe, use the train service to get to the airport in Athens if you prefer rail travel. Point-to-point tickets can be purchased at any rail station. A rail pass can also be purchased from RailEurope.com if you want a train pass that covers several countries and gives you unlimited travel for a set period of time.