You will need a test to board the ship - see the Celebrity website - but as I understand, it can be self-proctored. There are also requirements for entry into Spain.You may also need vax and a test to get into Spain, depending on your itinerary. Check the Spain health site Spain Travel Health (spth.gob.es) and info from the US Embassy in Spain, COVID-19 Information - U.S. Embassy & Consulate in Spain and Andorra (usembassy.gov).