Three Ways to Visit Santorini:
By Car:
1. From Sofia to Athens is 900 km. If you travel during the night it will take you approx. 12 hours.
2. Arrive at Pireaus port not later than 6 in the morning.
3. There is a boat at 7:25 - Blue Star Ferries. cost from 30 Eur (on deck) or alternatively 7:30 - Fast Boat from 55 Eur
4. It is 8 hours with Blue star and the arrival is at 15:00 and it is 4,5 h with fast boat and you will arrive at 12:00
5. Accommodation - I recommend Villa Manos: http://www.villamanos.gr/
By Bus
Get a bus at 4:30 so you can arrive at Athens not later than 5 in the morning
By Plane
Book a flight to Athens and than take the ferry to Santorini or:
Book a flight to Santorini (keep in mind that all flights are thru Athens.