The Mt Teide full hike is hard even for many adults, so basically it very depend on the child physical shape, but it’s definitely not for a child younger than 12 years. The minimal age to participate is 12 years. Children from 12 to 18 years old must be accompanied by their father or mother, or by both parents.  Book Climbing Mount Teide Peak - Private Tour with Permits now just with Booking Deposit on TripsPoint