Hantavirus outbreak on a cruise ship: Public health challenges.

•A rare hantavirus outbreak on MV Hondius in May 2026 caused 8 cases and 3 deaths.•Cruise ship confined spaces and HVAC systems facilitated aerosol transmission.•Jurisdictional disputes delayed critical medical evacuations.•Lack of isolation and diagnostics exposed cruise ship medical vulnerabilities.•Pathogen research and robust maritime emergency protocols are needed.