If you are a European Union citizen you do not need a Visa or a Passport in order to visit Greece. However you should always have your national ID card with you, in case you need to prove your identity to the local authorities. Driver's license, credit cards, tax cards etc are not accepted as proof of identity. If your country of origin is the U.K., Bulgaria, Ireland, Croatia, Cyprus or Romania, then showing your national ID card or passport is mandatory.
Rest Of The World
If you are a citizen of any country outside the E.U. then you definitely need a Passport. As for any Visa requirements, please go to the following link to check the Visa status of your country for traveling to Greece.
Visas for foreigners traveling to Greece > Countries requiring or not requiring a visa
Greek Embassies Around The World
If you need a Visa in order to visit Greece, then the place to get one is a Greek embassy. Below you will find a link to an extensive list of all the Greek embassies around the world.
Greek embassies abroad
Traveling to Turkey
If you have booked our cruise offering then you probably already know you will be visiting Kusadasi, in order to go to Ephesus, which is in Turkey. Going to Kusadasi on a cruise ship does not require a Visa. However, you do need to have your passport with you, which will be held by the cruise ship's personnel for the duration of your visit to Turkey. If you do not have your passport with you then you will be asked to pay a small fee, which depends on your country of origin (20$ for U.S. citizens)