Norwegian Cruise Line Holdings Ltd. has strict protocols that crew and passengers are expected to follow if they want to get on board as the company prepares to return to the sea.

All passengers coming through U.S. ports should be fully vaccinated no less than two weeks before boarding. Documentary proof is required.

Likewise, crew members should also show proof of vaccination at least two weeks before they begin work on board.

Basic health and safety protocols including wearing of masks, proper sanitization, COVID-19 testing and social distancing will be enforced.

Norwegian Cruise Lines will adhere to safety guidelines developed by the Healthy Sail Panel as the ships start sailing July 4 with 60% capacity.

Norwegian president and chief executive Frank Del Rio said the vaccination requirement is "ironclad" and with the other requirements in place, "no one can argue that being on a cruise ship under those conditions is not the safest place on Earth."

With Norwegian seeing revenues down by 80% last year, Del Rio is hoping that the situation will improve with improved health protocols for sailing.

The company submitted a proposal to the U.S. Centers for Disease Control and Prevention on how it can ensure safe travel for passengers and crew on its ships.

Del Rio said he was not "daring" the centers but he was looking forward to getting "feedback that suggests that this is not the best way" to get ships back out on sea.

More than a year ago, the centers released a no-sail order on cruises following multiple coronavirus outbreaks in ships, including several Princess Cruises ships.

The cruise ship industry as a whole saw revenue fall throughout the pandemic, but hopes are high for a recovery under the safest sailing guidelines that health groups and cruise companies are developing.

Meanwhile, the centers, in its guidance, recommended vaccinations for crew, passengers and port personnel, but did not make it a requirement.

Industry experts said the move will avoid potential conflict with Florida. The state is home to one of the biggest operation bases in the global cruise industry, but it banned businesses to require COVID-19 vaccination proof from customers.

Health experts have said that vaccination is crucial in safely resuming business in different industries. It remains to be seen whether the centers will change its recommendations in the coming months.