In recent years, the general public has become more aware of the health risks inherent to cruise travel, particularly the spread of contagious illnesses in semi-enclosed environments such as ships. However, less widely understood is the health hazard posed by hot tubs located on private balconies—an increasingly common feature aboard newer vessels.
The USA's CDC agency (Centers for Disease Control and Prevention) has been actively educating cruise operators about the potential for Legionella bacteria to proliferate in these hot tub systems. Unlike illnesses spread through close human contact, Legionella is transmitted through the inhalation of contaminated water droplets. When conditions allow the bacteria to thrive—such as in inadequately maintained hot tubs—it can lead to Legionnaires’ disease, a severe form of pneumonia.
While the incidence of Legionnaires’ disease among cruise passengers remains low, the presence of private-balcony hot tubs on modern ships introduces a growing area of concern. These tubs tend to see less frequent use and, consequently, may not receive the same level of routine disinfection and maintenance as their public counterparts. This inconsistency in upkeep can create an environment conducive to bacterial growth.
In recent months, RCI-Royal Caribbean has issued health notifications to passengers aboard the Symphony OTS, following reports of guests being diagnosed with Legionnaires’ disease after their voyage.
RCI relayed to passengers that the CDC had informed them of a case involving a guest who had sailed on the vessel, although the precise location of exposure remained undetermined. A similar notice had been sent earlier in the year, referencing two other passengers who had also become ill after cruising on the same ship.
Symphony of the Seas is not alone in facing this issue. In October 2024, the CDC disclosed that it had been alerted to a dozen cases of Legionnaires’ disease among travelers aboard two different cruise ships from separate cruise lines, spanning voyages between late 2022 and mid-2024. Investigations into both outbreaks identified private-balcony hot tubs as a common factor.
Public hot tubs are typically held to stricter cleaning schedules, thereby reducing the likelihood of bacterial growth. In contrast, private hot tubs are not subjected to the same maintenance standards, raising the potential for contamination.
The CDC continues to work with RCI to clarify the design and operational features that elevate the risk of Legionella proliferation and to promote improvements in maintenance protocols.
Royal Caribbean has stated it is taking additional sanitation measures on board and is complying with all CDC recommendations. The company emphasized its commitment to passenger and crew health, acknowledging that while most individuals exposed to Legionella do not fall ill, certain groups face heightened vulnerability. These include older adults, smokers (past and present), and individuals with specific pre-existing health conditions.
Passengers have been advised to monitor for symptoms such as coughing, fever, muscle aches, headaches, and shortness of breath. Those experiencing any of these symptoms are encouraged to seek guidance from a healthcare provider.