According to European Regulations, all travelers entering or leaving the European Union with more than €10.000, in cash, must declare the amount to Customs.

Customs controls at Greek points of entry distinguish between goods bought within the EU and outside the EU. When traveling to Greece from outside the EU you are allowed to bring in the following, provided you travel with the items and do not intend to sell them:

200 cigarettes, 100 cigarillos, 50 cigars, or 250g of tobacco
2 liters of still table wine
1 liter of spirits or strong liqueurs over 22% volume or 2 liters of fortified wine, sparkling wine or other liqueurs
60ml of perfume
250ml of tap water

For further information please visit the European Commission web site: https://ec.europa.eu/taxation_customs/individuals/travelling/entering-eu_en

Source: TCOA