It is widely believed that self-drive cars are the best way to get around in Greece. The short distances between islands, towns and archaeological sites can be covered far more effectively. The road conditions are undergoing rapid improvement. Self- drive rental agencies are omnipresent throughout major towns and cities. Most cars are manual transmission, however, some may have automatic facilities. Make sure you reserve in advance to avoid last minute snags.
The bus network in Greece is robust and quite regular. The KTEL is a government-subsidized network of buses. Thus, the buses are well-maintained, regular and cost-efficient. In case the bus is traversing to the islands, the cost of the ferry is worked out into the ticket itself.
Ferries regularly operate between the various islands of Greece. However, their frequency and availability is largely dependent upon the weather. During the rough season between the months of January and March, the sea can get quite stormy and travelling in such seasons becomes hazardous. Do check the road conditions before undertaking such journeys.