With a population of about 270 people, Thirasia lies very close to Santorini—in fact, both formed the same island until the huge volcanic eruption which is estimated to have taken place in 2nd millennium BCE, when it put an end to Minoan civilization and detached Thirasia from main island of Santorini.
There are five villages on the island, the largest one—which has a population of 150—sharing the same name with the island itself.
Thirassia is what Santorini used to be many years ago. There is nothing there beside peace and quiet. It is mostly visited by day trippers from Santorini, but if you go there for a few days you will be quickly part of the family. Be aware that hardly anyone on Thirassia speaks anything else than Greek.
Korfos , the "old Port" is where the day trip boats go. You cannot go there with a regular ferry or with a vehicle, and excursion boats are expensive. A much better option is to go to Riva, the "New Port". It is served about 5 times weekly by the regular ferries and a single trip is € 3. Schedules can be found at . There is also a small ferry owned by the island itself, which costs € 3.75, but it carries vehicles for free. Locals call it the "pantoffla". It goes daily from and to the island, but it is difficult to know when and where it goes. It serves the old and the new port and goes to Fira and Athinios and also to Oia if weather conditions allow. Be aware that if you ask in the travel agencies in Santorini they will in the first place have never heard about it, because they want to sell their daytrips.
Bring a Bike from Santorini or you don't! (3€ on a regular ferry, free on pantoffla). There is a bus though, but the nicest places are where the bus does not go. If you come for a longer period don't forget to bring some petrol as well, there is a petrol station, but not always petrol.
There are many very nice churches and Monasteries on Thirassia.
Relax, have a frappe, visit the many churches. There is a nice beach next to Riva.
You cannot buy much on Thriassia, bring your stuff from Santorini. The bakery has only bread, but it is made in a wood oven and is absolutely delicious.
in Riva you have two options: Kapetan Michalis catches his own fish. He has not much choice but what he prepares is delicious. Agistri is the souvlaki and where the locals meet. Try the Fava!
Korfos is the daytrip-tourist mekka, don't now if one should eat here.
Ask for Domatia in the Restaurants.
There is no Internet on Thirassia.