You might not have to wear a mask when you cruise this summer after all.In a major tweak to its new health guidelines for cruise ships, the U.S. Centers for Disease Control and Prevention (CDC) late Wednesday said cruisers on vessels where most passengers (95% or more) are vaccinated for COVID-19 won’t be required to wear a mask at any time.On vessels that don’t meet the 95% threshold, cruisers who are fully vaccinated will be exempt from mask-wearing requirements in all outdoor areas and any indoor areas specifically designated for fully vaccinated passengers, the agency said. On such ships, non-vaccinated passengers still will have to wear masks much of the time.For more cruise news, reviews and tips, sign up for TPG’s new cruise newsletter.The new mask rules are a huge change from the mask rules for cruise ships the agency issued just two weeks ago. Back then, the CDC said cruisers on all ships would need to wear masks in most onboard settings – whether or not they were fully vaccinated for COVID-19.Those rules, in turn, were slightly less restrictive than initial mask rules for cruise ships the CDC had unveiled in early May.The severity of the earlier rounds of mask-wearing rules for cruise ships led to widespread criticism of the CDC by cruise industry executives and cruise fans.“Preposterous” is how Norwegian Cruise Line Holdings president and CEO Frank Del Rio referred to the rules earlier this month during a conference call with Wall Street analysts.Norwegian Cruise Line Holdings is the parent company of Norwegian Cruise Line, Oceania Cruises and Regent Seven Seas Cruises.Sign up for our daily newsletterEmail addressSign upI would like to subscribe to The Points Guy newsletters and special email promotions. The Points Guy will not share or sell your email. See privacy policy.The rules included things that many cruise industry executives and cruise fans said were unworkable, such as a requirement that passengers wear masks even when seated for meals at restaurants. Passengers would only have been allowed to slip down their masks momentarily between bites of food and sips of drinks.Critics of the rules had noted in recent days that they were much more draconian than the guidelines the CDC announced earlier this month for Americans in most indoor and outdoor settings on land.The CDC’s mask-wearing rules for cruise ships are contained in a new “operations manual” for cruise lines the agency issued in early May and has been updating regularly. Dubbed the COVID-19 Operations Manual for Simulated and Restricted Voyages under the Framework for Conditional Sailing Order, it sets guidelines for cruise lines hoping to restart operations in U.S. waters in the next few months.Cruise lines have been in regular discussions with the CDC in recent weeks about the mask rules and other requirements in the operations manual.The CDC has been blocking all but the smallest cruise ships from sailing from U.S. ports since the COVID-19 outbreak was declared a pandemic in March of 2020, due to worries about the spread of COVID-19. But just this week it issued its first clearance to a line to restart operations.The agency on Wednesday approved a Celebrity Cruises plan to restart sailings out of Fort Lauderdale on June 26 with a single ship, the 2,908-passenger Celebrity Edge.Planning a cruise? Start with these stories:The 5 most desirable cabin locations on any cruise shipThe 8 worst cabin locations on any cruise shipA quick guide to the most popular cruise lines21 tips and tricks that will make your cruise go smoothly15 ways cruisers waste money12 best cruises for people who never want to grow upWhat to pack for your first cruise