As I read it, everything depends on where you first embark your cruise. It it is at the port of Athens (Piraeus). I bolded that part.
Greece Cruise Protocols
Country Requirements
Testing must be administered by a verified third party.
For cruises originating from a Greece port (i.e. Piraeus and Crete😞
Age
Vaccinated
Unvaccinated
< 12
Nothing required.
Nothing required.
12 to 17 Years
Nothing required for embarkation
NOTE: Guests who are unable to provide proof of completed series of one-dose or two-dose primary vaccination regimen at embarkation will be considered unvaccinated. Unvaccinated guests may be required to test occasionally throughout the voyage if deemed necessary by Greek Authorities. Guests would be responsible for the cost*
Nothing required for embarkation
NOTE: Guests who are unable to provide proof of completed series of one-dose or two-dose primary vaccination regimen will be considered unvaccinated. Unvaccinated guests may be required to test occasionally throughout the voyage if deemed necessary by Greek Authorities. Guests would be responsible for the cost*
≥ 18 years
Nothing required for embarkation
NOTE: Guests who are unable to provide proof of up-to-date vaccination regimen, including booster**, at embarkation will be considered unvaccinated. Unvaccinated guests may be required to test occasionally throughout the voyage if deemed necessary by Greek Authorities. Guests would be responsible for the cost*
Nothing required for embarkation
NOTE: Guests who are unable to provide proof of up-to-date vaccination regimen, including booster**, will be considered unvaccinated. Unvaccinated guests may be required to test occasionally throughout the voyage if deemed necessary by Greek Authorities. Guests would be responsible for the cost*
* Approximate cost per Covid-19 Antigen test is $95. The approximate cost per PCR is $199. This cost may vary and is the responsibility of the guest.
** All guests over the age of 18, whose primary COVID-19 vaccination will be beyond 270 days at the time of disembarkation from their voyage, must have a COVID-19 booster prior to embarkation.
In lieu of a booster 270 days after the primary series, guests may present a government recognized or official medical Certificate of Recovery.
For European Citizens, this would include an EU Green Pass or comparable certificate.
For all others unable to present an EU Green Pass (i.e. U.S. citizens) a doctor’s note, plus a laboratory confirmed PCR test result with the proper information (i.e. name, date, date of birth, positive result, etc.) will be accepted.