Neither is ideal. However, this is a case of apples and oranges. You're only on a plane for a few hours and you're masked. The air circulation is better on a plane. On a cruise ship you eat in crowded dining rooms many times for a week or more. There are many more cases of covid on a ship than a plane. Air travel is a must for the overall economy of a country. I had to cancel both plane travel and a cruise since this all started and I may have to cancel yet another cruise. I am not happy but the CDC is going by science and I believe in science.