These are the cleanest cruise ships this year, according to the CDC — including 18 with perfect scores

• The CDC randomly inspects and scores cruise ships to prevent the spread of stomach viruses.
• So far, in 2024, 20 cruise ships have received a perfect score.
• Norovirus can spread quickly on packed vessels.

Cruise ships don't always have a squeaky-clean reputation for being ultra-clean. After all, there's a reason they've been infamously dubbed "floating Petri dishes."

Not all floating resorts are created — or operated — equally.

The Centers for Disease Control and Prevention randomly conducts sanitary inspections on cruise ships throughout the year. So far in 2024, 20 vessels have received perfect scores.

At the same time, the public health agency has reported 10 bacterial and viral outbreaks — mostly norovirus — on ships since the start of the year.

Half have been on ships from Royal Caribbean Group's main cruise line and its Celebrity Cruises subsidiary. Overall, the number of outbreaks so far is fewer than in 2023, which saw 14 in total.

The highly contagious norovirus, also known as the stomach flu, is the most common virus to afflict cruises. These often-packed floating hotels create the ideal environment for the highly contagious bug to spread fast, typically through contaminated water, food, surfaces, and people.

Just as quickly, it can ruin your vacation — the four predominant symptoms are vomiting, diarrhea, nausea, and stomach pain.

To help mitigate these incidents, the CDC's Vessel Sanitation Program regularly inspects cruise liners and scores them from zero to 100.

The review — which includes checking common spaces such as kitchens, pools, and children's activity centers — is random and unannounced.

As expected, vermin and improperly stored foods are a big no-no. But inspectors are also closely watching behind the scenes for smaller, more-nuanced details such as how frequently the hair and lint strainer in the swimming pool is disinfected or the water temperature of the dish washer.

So far, in 2024, the CDC has performed 119 inspections. The majority scored above 95, and 20 (listed below) have received perfect marks:

• Carnival Spirit — Carnival Cruise Line (inspected September 3)
• Zuiderdam — Holland America Line (inspected August 24)
• Viking Orion — Viking Ocean Cruises (inspected August 18)
• Seabourn Odyssey — Seabourn Cruise Line (inspected August 16)
• Norwegian Jewel — Norwegian Cruise Line (inspected July 24)
• Oceania Regatta — Oceania Cruises (inspected July 24)
• Radiance of the Seas — Royal Caribbean International (inspected July 21)
• MSC Meraviglia — MSC Cruises (inspected July 9)
• Norwegian Bliss — Norwegian Cruise Line (inspected June 22)
• MSC Seashore — MSC Cruises (inspected May 26)
• Norwegian Sky — Norwegian Cruise Line (inspected May 23)
• Brilliance of the Seas — Royal Caribbean International (inspected May 16)
• Viking Polaris — Viking (inspected April 2)
• Celebrity Equinox — Celebrity Cruises (inspected February 25)
• Norwegian Breakaway — Norwegian Cruise Line (inspected February 25)
• Norwegian Escape — Norwegian Cruise Line (inspected January 27)
• Explora I — MSC Cruises (inspected January 25)
• Disney Fantasy — Disney Cruise Line (inspected January 24)
• Celebrity Ascent — Celebrity Cruises (inspected January 7)
• Norwegian Gem — Norwegian Cruise Line (inspected January 2)

This time last year, 29 ships had achieved 100. By the end of 2023, 34 vessels racked a perfect score.

Correction — October 17, 2024: An earlier version of this story contained an incorrect photo caption. The causes of outbreaks on Royal Caribbean's Radiance of the Seas ship were norovirus and salmonella, the CDC found.

Also, an earlier version of this story incorrectly stated there are 18 ships that have received perfect scores so far this year. There are 20.

Also, so far in 2024, the CDC has performed 119 inspections, not inspections on 119 individual ships, as some were repeat inspections.