Yes, Norwegian Cruise Line (NCL) generally allows passengers to bring hair straighteners (flat irons) and curling irons on board. Unlike clothes irons or steamers, which are strictly prohibited due to being significant fire hazards, hair styling tools are classified as personal grooming devices and are permitted as long as they are used with "proper caution." However, ship security has the right to confiscate any device if they believe it is malfunctioning or poses a safety risk; in such cases, it would be returned at the end of the cruise. To be safe, it is always recommended to unplug your straightener immediately after use and never leave it unattended while hot to avoid any issues with stateroom inspections.