Holland America Line and Princess Cruises are once again requiring guests to wear face masks during their sailings in Alaska.

In letters sent to booked guests and distributed onboard the ships sailing in the region, the Carnival Corporation-owned brands stated that the measure is related to a recent spike in COVID-19 cases.

“Out of an abundance of caution due to the rise in positive COVID-19 cases throughout Alaska, all guests will be required to wear face masks at all times while onboard, except when eating or drinking or in their own staterooms,” Holland America Line said.

The premium cruise operator also highly recommends masks while outdoors in large gatherings or if physical distancing cannot be maintained.

While the face masks are now required on all cruise line-sponsored transportation, Holland America is “strongly recommending” masks to be worn while ashore as well.

“As you may be aware, positive COVID-19 cases are currently on the rise throughout Alaska. Consequently, out of an abundance of caution, we will be requiring guests to wear face masks while onboard except when eating or drinking or in their own staterooms,” Princess said in a similar statement.

Like Holland America, Princess also highly recommends masks while outdoors in large gatherings or if physical distancing cannot be maintained.

Additionally, passengers will also be required to wear the face masks while on all Princess Cruises-sponsored transportation, such as motor coaches and rail.

“We also strongly recommend wearing masks while shore, particularly when indoors, on public transportation or in crowded areas,” Princess added.

Both companies also stated that guests who do not comply with the mask requirements may not be permitted to board the ship or may be disembarked.

After returning to the region with limited operations in 2021, Holland America Line and Princess Cruises are sailing full programs in Alaska this year.