Mark SimpsonCommunities correspondent, BBC News NI
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The royal couple smiled and laughed as the princess took part in a rope-throwing exercise organised by firefighters
The Prince and Princess of Wales have met recently-qualified firefighters during their first joint visit to Northern Ireland in three years.
Their trip began with a tour of the new Northern Ireland Fire and Rescue Service (NIFRS) Learning and Development College in County Tyrone.
The couple joined in some of the training exercises at the £50m state-of-the-art training site, at Desertcreat just outside Cookstown, which opened in May.
NIFRS trainee Caoimhe McNeice, from Belfast, who spoke to the media on its first day of operations, was among those who greeted the royal guests on Tuesday.
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The royal couple met recently qualified firefighters Caoimhe McNeice (centre) and Piarais McCaffrey (right)
The multi-million pound training centre represents the biggest capital investment in the fire service's history.
It includes a tactical firefighting facility, a floodwater rescue facility, a replica village and a training warehouse.
The royal couple were given a tour of the 50-acre site and were taken to and from different areas in a fire appliance.
They were shown training exercises including flood-water and rope rescues and they both joined in for one of the rope-throwing exercises.
The visit coincides with fire safety week.
Chief fire officer Aidan Jennings described it as a "proud and unforgettable day for our service".
The Prince and Princess of Wales met staff at a new training centre used by the Northern Ireland Fire and Rescue Service outside Cookstown
Stormont's Health Minister Mike Nesbitt, whose department oversees the fire service, was also at the event.
When he was introduced to Prince William he said with a smile: "Welcome back to the mainland."
Minister Nesbitt later decribed the visit as a "significant recognition of the courage and commitment of our firefighters and dedicated staff".
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The royal guests were given a demonstration of a water rescue
. Chris Jackson/Pool via REUTERS
The NIFRS flood water rescue simulator is one of only two in the world at a fire service training facility, according to Kensington Palace
Kensington Palace said the NIFRS site provides "opportunities for young people from across Northern Ireland to train to become the next generation of firefighters".
The prince and princess have a number of other engagement's scheduled on their one-day trip.
The palace said they would spend their time "visiting innovative organisations that showcase growth and investment in rural areas".
Their itinerary also includes engagements at sites which "demonstrate entrepreneurial and creative opportunities for young people."
Caoimhe McNeice and Piarais McCaffrey were among the first recruits to train at the state-of-the-art facility
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The Princess of Wales smiled while taking part in a training exercise during a visit to the Northern Ireland Fire and Rescue Service Learning and Development College