By Air
The national airline, Olympic Airways, operates flights between many cities and islands, including Athens, Rhodes, Crete and Thessalonica. Two other airlines- Cronus Airlines and Aegean Airlines- also operate flights between popular tourist destinations, although on a smaller scale. Flights tend to be much more expensive than other means of transportation- for instance, a flight from the mainland out to one of the islands can cost as much as three times the ferry fare. Landing by that little aircraft on napkin sized airstrips is quite an experience, though.
Note that reservations must be made well in advance, especially during the summer.
By Road
Buses in Greece are the most popular form of public transport since the train system is not as extensive. Operated by KTEL, a wide network of long-distance buses covers nearly all of Greece, linking even fairly obscure towns and villages to the main urban centres. In addition to the KTEL buses, there are special intercity express services. Bus travel in Greece can be a very varied experience- slow, overcrowded buses and long routes is something you should be prepared for. In the tourist season be sure to buy your tickets in advance.
Taxis are a good alternative to buses, especially in and around large cities. They're usually quite affordable, and many tourist-savvy cabbies are good at giving you a guided tour of all the sights.
You could, of course, hire a car- there are plenty of rental agencies in all the important tourist destinations. But be warned: it's not easy (and not much fun!) driving a car through a crowded and narrow street in a Greek city. Mountain roads, if not crowded, are equally treacherous and are often not in too good a condition.
By Ferry
An extensive ferry network connects the mainland to the islands and this is a popular and convenient way of getting around the Aegean Sea. Most ferry routes include a four or five port route and if you buy a round ticket you can split the ticket - meaning get off at the port of your choice and spend a day or two and get on to the ferry again a couple of days later and continue. The only problem here is that ferry services are irregular and often delayed so you have to be patient.
`Flying Dolphins' or hydrofoils are the express vessels which travel between the islands and the mainland ports. Though more expensive than the regular ferries, the Flying Dolphins are a great deal faster and more comfortable.