climbing a tree without being secured by a climbing rope.
free climb (Wikipedia)
Free climbing is a form of rock climbing in which the climber can only use climbing equipment for climbing protection, but not as an aid to help in their progression in ascending the route. Free climbing therefore cannot use any of the tools that are used in aid climbing to help overcome the obstacles encountered while ascending a route. The development of free climbing was an important moment in the history of rock climbing, including the concept and definition of what determined a first free ascent (or FFA) of a route by a climber.