A frequently asked question of travelers in Greece is whether they should rent a car. The primary advantage of having a car is that you can cover a lot more ground per day if you're traveling in rural areas or on the larger islands: you can get almost anywhere in Greece by bus, but some isolated villages may only have one or two buses per day, and having your own car means you don't have to wait in the summer heat for the bus to come. Almost all archeological sites are accessible by bus, but at some of the more remote, less famous, sites, the bus may drop you off up to a mile away from the site, while with a car you can almost always get right to the site via at least a rough road.
On the other hand, going car-free in Greece is not only possible, but offers significant advantages, while driving involves a number of disadvantages. Though many people find driving in Greece easy and even pleasant, others are concerned by the high accident rate (one of the highest in Europe), the national reputation for risky driving, and the presence of many twisty mountainous roads, sometimes hugging the side of a cliff. Gas is as expensive as anywhere. (For more on driving conditions in Greece see below.) Driving in Athens and other big cities can be a frustrating, and sometimes hair-raising, experience, and finding parking can be very difficult. And having a car greatly restricts your flexibility when island-hopping, since only the larger, and usually slower, ferries offer car transport, which must be paid for in addition to your passenger ticket. Traveling by bus is not only cheaper but offers a greater chance of striking up conversations with both locals and other travelers than going by car. Language is not usually a problem for English speakers in using public transit: wherever there is significant tourism in Greece bus schedules are posted in English, and bus drivers and conductors, as well as taxi drivers, will understand at least enough English to answer your questions
Public transit can be supplemented by taxis (see below), which in many places, especially the islands, offer fixed rates to various beaches, which can be affordable especially if the price is shared among several people. And on many islands it's possible to get places by walking, which can be a pleasant experience in itself.
By bus and train
Intercity buses are a very popular option for domestic travel. KTEL is the national government-subsidized network of independent businesses which cooperate together to form a dense route system serving almost the entire country. The system is efficient, reliable, and relatively inexpensive. It serves both long and short distances, including routes from major cities to islands near the mainland, such as Corfu and Cephalonia (in such cases, the ferry crossing is included in the price of the bus ticket).
Trains are a better way to get around, but the national rail system (OSE, http://www.ose.gr/
) is extremely limited. This is due to neglect after the arrival of large scale automobile use and air travel, and also due to past technological difficulties in surmounting the country's difficult terrain. The importance of rail travel is now being rediscovered, and the national rail network is currently under major renovation. The project's completion is still a long way off. There has been extensive (and continuing) modernization of the Athens-Thessaloníki corridor, with travel times being slashed.
Exploring the country by automobile can be an extremely rewarding experience, allowing you to explore the incredibly scenic and varied terrain of the country's coastlines, interior, and islands, at your convenience. Roads are usually well-marked and well-maintained, and billions of Euros are being poured into expanding the nation's network of multi-lane freeways. Because of the rapid expansion and improvement of the nation's road system, it is advised to have the most updated road map(s) possible. Many of the newer motorways are toll roads, and fees can be expensive. Road signs in Greek are usually repeated with a transliterated version in the Latin alphabet.
Automobile rental agencies are present throughout the country, especially in major cities and in highly touristed areas. The automobiles offered are overwhelmingly manual transmission; automatics do exist, but it is advised to reserve one in advance. Gasoline/petrol prices are steep, but relatively inexpensive in comparison with many other EU countries. Some automobile rental agencies and insurance policies do not allow taking the car out of the country.
Drivers who do not hold an EU driver's certificate must carry a international driver's permit obtained in their home country. This may not be required when renting a car, but will certainly be required if involved in an accident or pulled over by the police for a traffic citation. Insurance policies may be void if the driver is a non-EU driver without an international permit.
For those used to driving in North America, driving in Greece can be a challenge. To them Greek (and other European) drivers might appear agressive. Also the nation's topographic reality poses challenges by forcing many narrow roads in mountainous regions to take several twists and turns. Roads in towns and villages can be surprisingly narrow as well. If cars meet on a narrow stretch of road it is customary for one driver to find a spot to pull over and let the other driver pass. At times, one driver will need to back up for the other. Adherence to this practice is expected and failure to do so will bring the ire of your fellow drivers. Drive slowly through villages and small towns, because there are often pedestrians in the roadway. Another major difference between driving in North America and Greece is the range of speeds at which vehicles travel, particularly on the highways. While speed limits are as high as 120 kph (75 mph), some vehicles will be traveling as slowly as 60 kph (40 mph). Other vehicles will travel at speeds well in excess of the posted limits and can come up from behind very quickly.
The frequency, reliability and availability of Greek ferries are largely dependent upon the time of year. For instance, during the winter off-season (January to March), the weather on the Aegean can be extremely rough and boats are often kept in port for days at a time. This type of delay is extremely unpredictable (it is not a decision of the ferry companies, but rather, that of the port authority) and determining when a harbored boat will actually set sail is near impossible. Therefore, travellers in off-season should build some flexibilty into their schedule and not plan on departing an island in the morning and catching a flight home in the afternoon. On the opposite end of the spectrum, ferries in August fill up due to the National Holiday (Aug 15), so travelers should plan ahead.
As for routes, during high-season there are extensive connections from Athens and quite a few in-between islands for "hopping." Again, in the winter, some of these ferries run once, maybe twice a week.
Visitors to Greece planning to travel by ferry should be aware of some potential complications. First, it can't be assumed that you can get from any given island to any other island every day of the week. The Greek ferry system is basically a hub-and-spoke system, with the spokes radiating from Piraeus out to the various island groups. As a result, boats within the groups are fairly frequent, but less so between the groups. Sometime islands which are geographically close together are in different groups: for instance, the Western Cyclades (Serifos, Sifnos, Milos) look very close on a map to the Central Cyclades (Naxos, Paros, Mykonos,) but these groups are on different spokes, meaning you can usually in summer get from one island to another in the same group on any day, but boats between the groups, e.g. Naxos to Sifnos, may be significantly less frequent. Second, trying to find advance information on ferry schedules can be frustrating: unfortunately there exists no single official comprehensive source for Greek ferry schedules either in print or on line, though there are a number private sites run by travel agents or other businesses which claim to give comprehensive schedules , and many of the individual ferry companies have web sites giving their schedules, in some cases offering the ability to book and pay for tickets on line. (Ferry schedules are also always posted at the boat ticket offices in departure ports.) Next, though getting a ticket usually isn't a problem, some boats to the most popular destinations, especially those leaving at the most convenient times, do sell out in high season or on holiday weekends. Finally, though ferries nowadays usually run on schedule, weather, strikes, and mechanical breakdowns still can occasionally delay them. None of these problems are insuperable, but they do mean you shouldn't try to micromange your ferry itinerary too strictly in advance: be flexible, and always have a backup plan. And it's always a good idea not to count on taking a ferry from the islands to get back to Athens the same day your plane leaves, even if boat schedules theoretically should enable you to do this: this will probably work, but there's enough of a chance it won't to make it prudent to plan on getting back to Athens at least one day before your flight.
There are three ports in Athens: the main port Piraeus and outlying Rafina and Lavrio port. These serve all islands, but central Cyclades islands such as Tinos and Mykonos, it is often better to leave from Rafina.
Ferries are about the one thing in Greece that leave on time so be prompt. New "fast ferries" are cutting distance times in half but prices are slightly more expensive. Sometimes, it is more practical to fly, especially to Crete or Rhodes. However, flights are usually more expensive. Santorini is 8 hour slow boat from Athens but the entrance view from the boat is spectacular.
The major ferry companies operating in Greece include:
-Aegean Speed Lines (Cyclades)
-Agoudimos Lines (International and Greek Islands)
-ANEK Lines (Crete and international)
-Blue Star Ferries (Italy-Greece and Aegean Islands)
-Euroseas (Saronic Gulf)
-Hellenic Seaways (Aegean Islands)
-Minoan Lines (Italy-Greece and Crete)
-SAOS Ferries (Aegean Islands and northern mailand)
-Superfast Ferries (Italy-Greece)
-Ventouris Ferries (Italy-Greece)
Schedules and web sites for some very local ferry services may be found on the destination pages for the relevant islands or ports.
Though this guide usually doesn't list transportation web sites unless they're run by a government or by a primary transportation provider (like the shipping companies listed above), because of the great interest in Greek ferry schedules and the fact that there's no single official source for them, in this case readers are referred to the comprehensive Greek ferry schedule sites at Greek Travel Pages  and OpenSeas .
See also Continental Greece in ten days
The nation's domestic air travel industry is dominated by Olympic Air (http://www.olympicair.com/
) and its growing competitor, Aegean Airlines (http://www.aegeanair.com/
). Both airlines offer an extensive route network within the country, including service connecting several islands to the mainland. Aegean Airlines and Olympic Air offer e-tickets, which only exist as an e-mail or a web page with booking confirmation. It should be provided printed at the check-in desk at the airport (no need to visit airline office).
There are many taxis in Greece, but in the large cities, Athens in particular, getting one can be quite a challenge! Taxi drivers are known for being quite rude and not taking you if they feel like it. You hail taxis like in any other large city, but in Athens many taxis will refuse to take you if they don't like your destination. If you need a taxi during rush hour, it can be next to impossible to find one going outside the perimeter of Athens(they all say they are going home, or worse, they ignore you). If you want to go to a beach in the southern suburbs such as Glyfada, what I have found helpful in a moment of desperation is to find a hotel and get a taxi from there, much easier. A word about luggage and transport from the airport. Most taxis will not take more than three people but will load their trunks with luggage hanging out if need be since the cars can be very small. If you need a taxi from the ferry at night from Pireaus, well all I can say is good luck. The drivers who wait outside are looking to take at least three different individuals going in the same direction so they can charge three fares! I found if you are two or three people, only one person should hail the cab and then if he agrees to take you, have the other(s) jump in. The taxi situation has improved since the Olympics when they retrained all the drivers to be more polite, but getting a cab in Athens can still be a real pain in the neck!