Updates to the Centers for Disease Control and Prevention's (CDC) guidance for cruises saw Norwegian Cruise Line change its masking and testing policies.

For cruises working with Norwegian Cruise Line, starting March 1, the mask mandate on board ships will be lifted. The cruise line said that due to the "100% vaccination" of crew and guests age five and over "face coverings are not required while onboard."

The cruise line clarified that it still encourages passengers to wear masks indoors and wherever six feet of social distancing between others is not possible.

The updated guidance from Norwegian does not apply to European sailings, which will require guests to wear a mask due to local government regulations.

The cruise line's testing policy has also seen an update. As of March 1, “all guests will be required to provide proof of a negative COVID-19 antigen or PCR test result administered by a verified third party or via medically supervised home test...within two days prior to boarding for cruises originating in a U.S. port,” the guidance reads.

“Three days prior for voyages departing from a non-U.S. port,” Norwegian's guidance clarified.

The changes to the Norwegian Cruise Line happened as the CDC updated its guidance to add an optional program cruise lines working in U.S. waters can participate in. Non-participation will see a cruise line fall into the "gray" zone, meaning that the CDC can neither verify nor trust that a cruise line’s safety protocols are in line with current CDC guidance.

Though the program, which includes detailed vaccination status tiers, is optional, the cruise lines that do not opt-in will still be regulated by the CDC, reports USA Today.

The cruise line industry has already voiced its frustration with the updated guidance, with Cruise Lines International Association calling it “out of step with the actual public health conditions on cruise ships and unnecessary in light of societal trends away from more restrictive measures.”

The CDC plans to reevaluate its guidance on March 18.