Greece has been a leading cruise destination this summer with a large number of cruise lines operating around the islands.
COVID protocols are changing all the time, but at time of writing (October 2021), adults need the following: proof of double vaccinations or a negative antigen test to get into Greece (as well as a Passenger Locator Form); and port authorities require another rapid COVID-19 test before boarding your ship.
Mid-week tests onboard are also mandated, too, particularly if you’re calling at Piraeus for Athens (note some are included in your cruise fare, while others charge).
You will also need to show proof of double vaccination to enter the islands' museums and indoor attractions, and wear a mask.
Here's a guide to a selection of Greece's most popular islands and what each is mandating in terms of testing and proof of vaccination.
Your ship may arrange an antigen test before you arrive at Piraeus, a port requirement at the moment. From Piraeus it's a slow traffic-choked drive to Athens city centre, 12km away. Public transport has been cut because of COVID, although the Athens Suburban Railway is the fastest and cheapest route from Piraeus to the centre.
Masks are compulsory on the train and visitors still wear them at the Acropolis, near Syntagma station, where proof of vaccination is required even though it's an open-air site. Photo ID may be requested too.
This year's 200th anniversary of Greek independence from Turkey was marked by the reopening of the National Gallery in Athens after an eight-year transformation but you'll need proof of vaccination or a negative antigen test to visit and groups are limited to 20.
It's a 45-minute walk to UNESCO-listed Old Corfu Town from the cruise terminal, or you can put your mask on and take a taxi or local bus. Masks are mandatory for all public transport, shops, galleries or museums in Greece.
You'll also need proof of double vaccination for museums and some want photo IDs, including Corfu Museum of Asian Art where there's the option of showing a recent negative rapid test confirmation for children not fully vaccinated.
The museum is in the neoclassical Palace of St Michael and St George, built for the British Lord High Commissioner in 1864 when Corfu was a British Protectorate.
Opposite is the Esplanade, with a cricket square and bandstand, and across a busy road to the right is a maze of narrow streets full of pretty shops, while to the left is the massive Venetian-built Old Fort built in the Adriatic Sea.
Cruise ships dock at Crete's Souda port, seven km from the 14th-century Venetian harbour town of Chania, where you can easily spend a day walking the harbour wall to see the 16th-century lighthouse, shopping in the narrow streets nearby and swimming at the town beach.
Local buses run a shuttle service for less than 2 euros from the dock gates. Masks must be worn on buses and in shops and museums but there's a relaxed atmosphere in town.
Its quirkiest attraction is the Greek National Football Museum near Old Chania Market, which celebrates Greece's 2004 European Championship win and has shirts from stars including David Beckham and Cristiano Ronaldo.
No need for buses and masks when you take a short walk from your ship into Rhodes Town. The maze of alleyways takes you past countless shops up into the UNESCO-listed medieval Street Of The Knights and massive Palace Of The Grand Master Of The Knights Of Rhodes.
To visit the palace you need proof of vaccinations or recent test and they will ask for ID, so don’t forget it. Masks are also obligatory.
Consider buying a 10 euro combined ticket to get you into the palace, Archaeological Museum, Decorative Arts Collection and Our Lady of the Castle.
Before getting back on your ship dock officials may want to check you with a temperature gun.
Whether docking at Mykonos or arriving by tender you're likely to be met by officials with temperature guns but once past them you can admire the brilliant white perfection of the narrow shopping streets of Chora, the real name for Mykonos town.
Dominated by expensive jewellery and clothes shops (it's the place for organic linen) once you've taken your selfie in Little Venice where the sea laps the restaurant tables, you can walk up to the famous windmills then follow a coast path to a hidden cove or further on to unspoilt Megali Ammos beach, where rustic Joanna's Niko's Place Taverna sits on the rough sand. If you choose to visit the island of Delos (offered on many ships as an excursion), you won't need to wear a mask when visiting the open air ruins, but you will on the boat over and in the museum.
Back in town overlooking the sea is the Folklore Museum, which opens late afternoon but if sailaway won't allow a visit the castle ruins next door are free to walk through and part of an archaeological site that is still being explored.
Mykonos was subject to a snap lockdown in July due to the Delta variant, and as a result health and safety rules are strictly enforced -- the island famous for its nightlife is still limiting large gatherings, dancing and parties (should your ship overnight or leave late).
You'll need to wear your mask as soon as you head up to Thira in the cable car. Also note that although they can take six, they are restricted to four people.
If you choose to take a cab or a bus to any of the beaches, you will also need to wear a mask.
And if you choose to visit the most popular museums in Thira -- the Folklore Museum, Prehistoric Thera and the Archaeological Museum -- you'll need to mask up (note you don't have to if you visit the open air site of Ancient Thira) and show proof of double vaccination.
There are just two streets of tourist shops and a row of waterside restaurants but Katakolon is the port for tours to Olympia, where the first Olympic Games were held in 876BC.
It's very relaxed in Katakolon and although masks are required to visit shops the little Tourist Fun Train that takes you to the Mercuri Winery and Andreas beach has open sides so no obligation to wear them.
Olympia, 40km away, takes it far more seriously. No masks are needed to see the ruins but for Olympia's Archaeological Museum, with its exceptional collection of excavated statues and bronze figures, you'll need to mask up and show evidence of full vaccination.
Groups are limited in size and must keep moving, stopping to listen to guides only in the most important rooms. Limited numbers may mean some queuing to get in, although there are fewer than half the usual visitors this year.
Tip: Don't try to get to Olympia by train from Katakolon, the five trains a day service has been reduced to one.