The entire cruise industry has a long, long way to go when it comes to reducing airborne COVID transmission. I've been on 2 cruises in my life (about 20 and 25 years ago) and the minute I walked into that ship the overwhelming smell of air freshener hits you as you're walking down the corridor to your room and you enter your room. Within a few hours, you get used to it and you can't seem to smell it anymore but it is still there. Cruise ships just like high-rise office buildings have their HVAC systems designed to deliver the most economical heat and cooling possible and that means recirculating the maximum amount of interior air possible and only delivering enough fresh air to maintain regulated maximum levels of CO2 and such. Cruise ships and office buildings were never required to install HEPA level filtration in their HVAC systems. In short, wear a mask all you want in public on a cruise ship but when you close your cabin door and take your mask off you're breathing the same unfiltered recirculated air everyone else is breathing on that ship in your HVAC zone. The cruise lines can try all they want but until they replace very, very cheap air freshener with very, very expensive HEPA air filtration systems every test-cruise they run is going to become problematic in my opinion just as prior cruises at the dawn of COVID ended up with such disastrous results.
This brings me to the airlines... HEPA filtration was embraced by the airlines decades ago for one reason... Smoking used to be allowed throughout planes and then they established smoking and non-smoking sections but it didn't matter if you sat in smoking or non-smoking everyone was stuck in the same tube smelling the same smoke-filled air. HEPA filtration was introduced to reduce the second hand smoke that was pumped throughout the plane. Now, with COVID upon us the airlines have increased the 100% change of interior air to every 2-3 minutes on top of HEPA filtration.
The bottom line is (and the statistics prove to date) that you are far, far safer being crammed into an airplane cabin and flying non-stop for 7 days straight with everyone on board with you than spending 7 days on a cruise ship walking about, practicing social distancing, and sleeping in that cabin without wearing a mask thinking you are safe in there when you are not. It's all about the HEPA filtration and how often the entire interior volume of air everyone is breathing is replaced.
