The royal couple were in awe as they took in the towering weathered sandstone peaks, one of the country's most iconic landmarks. They also visited the spectacular vertical cliff at Narrow Neck Lookout at Katoomba.
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At one point, daredevil William was seen peering over the 100-metre cliff face as he and Kate watched abseilers dropping to the bush below.
"He took a bit of a lunge and a few people held their breath, gasped and readied their hands to grab him," Damien Cooper, manager of the Blue Mountains Youth Service, told Australia's Daily Telegraph.
"He was fine, of course, he knew what he was doing. I think his military background prepared him well for it."
Tim Williams of the Blue Mountains Adventure Company added, "He was very calm on the edge; he didn't worry about the safety briefing to stay a fair distance back.
Prince William and Duchess Kate were aware of a security risk
"He just stepped up to have a cool look over. He said it would be nice to come back another time and have a go himself.
"They were both keen, it was just their attire that held them back. It's a bit difficult to abseil in a suit and dress."
The couple's appearance came as police detained two men acting suspiciously near the Duke and Duchess.
The two suspects, aged 21 and 37, were stopped and searched after "acting suspiciously" and "causing a disturbance" in the village of Winmalee shortly before the royals were due to arrive,
"They were stopped and searched and moved on from the area prior to the motorcade going past," a source confirmed.
Prince William and Duchess Kate met families of bushfire victims
One of the men was wearing a mesh vest with pro-Israel stickers on it.
During their time in the Blue Mountains, William and Kate met with families affected by the bushfires which swept through the area in October last year.
The royal couple displayed their kind and caring side as they listened to the victims' accounts - even spending ten minutes talking to one family - and offered their sympathies for those who lost their homes just six months ago.
They also met with fire service personnel who had been directly involved with the devastating bushfires.