Cruise ships are often called “petri dishes” and other derogatory names due to the tremendous crowds of thousands of guests in the same spaces, but illness outbreaks aren’t confined just to the world’s largest ships.

A gastrointestinal outbreak has been reported aboard Seven Seas Mariner, a luxury ship from Regent Seven Seas Cruises with just 1,089 guests and crew aboard. The outbreak is the first reported in 2026 by the Centers for Disease Control and Prevention (CDC).

The outbreak happened on the ship’s most recent sailing, a journey from Miami, Florida to Honolulu, Hawaii. Seven Seas Mariner set sail from the Sunshine State on Sunday, January 11, 2026 and transited through the Panama Canal, visited multiple ports in Central America and Mexico, and moved on to Hawaii, arriving in Honolulu on Sunday, February 1.

A total of 21 guests out of the 631 passengers onboard reported diarrhea, while six of the 458 crew members also reported the illness. At this time, the causative agent has not been identified.

Outbreaks in US waters must be reported to the CDC whenever more than 3% of either guests or crew report gastrointestinal symptoms.

While this outbreak onboard Seven Seas Mariner has impacted just 1.3% of the luxury ship’s crew, a total of 3.3% of guests reported symptoms, necessitating the report.

Because the sailing has been a lengthy one, however, it is important to note that individual illness reports may not be simultaneous. Reports made to the CDC cover the total number of cases reported during a single voyage, and it is possible that just a few individuals were sick at any one time during the sailing.

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Seven Seas Mariner has already continued sailing in Hawaii as part of a longer overall itinerary. The 154-night roundtrip world cruise sailing from Miami will now head for unique destinations in French Polynesia and the South Pacific, New Zealand, Australia, Asia, India, and Africa before eventually returning to Florida in mid-June.

Guests can book just individual segments of these types of long voyages, which is why the report has already been made to the CDC.

Response to the Outbreak

Once gastrointestinal cases were identified on board, Regent Seven Seas took immediate action to minimize the potential spread of a contagious illness.

This includes standard response measures such as increasing cleaning and disinfection in all public areas, particularly high-contact surfaces such as railings and elevators.

Guests and crew members reporting symptoms were isolated, and samples were collected to be tested to confirm the causative agent. That testing has not yet been completed.

Guests onboard would also have been encouraged to use proper handwashing techniques, particularly after using the restroom and before meals, to minimize any contagion. The CDC’s Vessel Sanitation Program (VSP) is monitoring the situation in case further steps may be necessary.

First Outbreak of the Year

The outbreak aboard Seven Seas Mariner is the first one reported in 2026, but it undoubtedly won’t be the last. In 2025, a total of 23 outbreaks were reported across all cruise lines and vessels of all sizes.

The most recent to have impacted a Regent Seven Seas vessel was aboard Seven Seas Explorer at the end of April and into mid-May 2025, with 24 guests and crew members affected. No causative agent was ever determined in that outbreak.

The Seven Seas Explorer outbreak was the only incident noted aboard a Regent Seven Seas ship in 2025, but other lines impacted by outbreaks include Sea Cloud Cruises, Silversea Cruises, Princess Cruises, Royal Caribbean, Holland America Line, Cunard, Celebrity Cruises, and more.

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