Windstar Cruises has resumed operations with a seven-day roundtrip voyage from Athens.
The sailing is the first of the six-ship line’s phased restart through to November.
All guests onboard sailing yacht Wind Star were required to be fully vaccinated against Covid-19.
Windstar will sail only with fully vaccinated crews too.
The voyage from Athens will visit Nafplio, Monemvasia and Patmos, as well as they islands of Santorini and Mykonos where there will be shore excursions.
Windstar will sail the itinerary on a near-weekly basis through to October.
Its remaining five ships will make their returns over the coming months, with guests and crew subject to new health and safety measures.
These include testing, social distancing and mask wearing, beyond vaccination.
"All of Windstar’s crew aboard Wind Star have been vaccinated, and Windstar is ensuring that crew are vaccinated on all Windstar yachts when they begin sailing on revenue cruises with guests," said the line, which claims to have been among the first to require guest vaccinations and pursue full crew vaccination.
"Procuring doses for Windstar’s primarily international crew has been challenging, but line officials have now successfully sourced vaccinations for crew aboard all six yachts," the line added.