Greece is very safe for tourists. Violent crime is rare; the main concerns are petty theft in crowded Athens neighborhoods (Monastiraki market, metro system) and occasional scams at tourist-heavy restaurants overcharging for seafood. Always check the price of fish sold by the kilo before ordering.
Sea safety deserves attention: the Aegean can be choppy and winds pick up suddenly. Always check ferry cancellations during Meltemi wind season (July–August). Lifeguards are not always present at beaches — swim with caution.