Specialist roles typically exist only on larger vessels and super yachts above 50m+. These roles cover all departments and can include (but not limited to) Dive Instructor, Nurse, Watersports Instructor, Masseuse, Beautician, Body Guard, Private Security, ETO, Helicopter Mechanic, Helicopter Pilot among many others. In many cases these roles are in addition to your primary position onboard. For example, you maybe employed as a Deckhand but from time to time you'll be asked to assist the owner on a diving trip or water sports tuition for example. It is not unusual for these specialist skills to demand additional pay from the main role you are employed.