While visiting Towers Residential Outdoor Education Centre in Betws-y-Coed, Conwy, the royal couple ascended a climbing wall.
Earlier, they visited a photography project run by charity Mind in Caernarfon, Gwynedd.
They also saw the work of GISDA which provides training for young people.
Twm Griffiths, who works at the charity's training centre in Caernarfon, said the couple were rushed off their feet.
He said: "They didn't have time for a coffee. They have a very busy day."
Afterwards, the couple visited the Men's Shed in Denbigh, Denbighshire - a social group involved in community projects.
The pair chatted with a small crowd outside, including four-year-old Esme who presented Prince William with flowers and asked about Prince George.
William said his son was "loud" and thanked her for the flowers, which he said he would give to Catherine.
Men's Shed director Phil Williams said the couple were given a tour of facilities, including an allotment and a woodwork workshop, and were very interested in the project.
Member Alan Maddocks presented them with a gavel and bowl which he carved on a lathe, a skill he has learned since joining the group.
"They were very friendly. On the way out they both shook my hand," he said.
The Duke and Duchess of Cambridge have been in north Wales to meet organisations which support young people and tackle mental health issues.