Norwegian Cruise Line is putting three of its ships back in the water after a one-year pandemic hiatus, with plans to resume sailings in the Greek islands and the Caribbean in late July and August.

The cruise line expects that the limited re-openings announced Tuesday will attract many Americans, even if the ships can’t stop at U.S. ports.

The company said that all passengers and crew members will need to be fully vaccinated and tested for COVID-19 before boarding.

Shares of parent Norwegian Cruise Line Holdings Ltd. rose 6% in late-morning trading.