When your life literally hangs on a thread you will want one that is strong, firm, and durable such as the Samson Arbor-Plex Climbing Line.
The Arbor-Plex is a kernmantle rope with an interior made of polyolefin fibers. Polyolefin is a new class of polymer that is both tough and elastic giving the rope its durability and flexibility. The mantle, or the exterior sheath, is made of Duron II™ polyester jacket fibers. These fibers are resistant to abrasion and wear keeping the kern safely covered.
Although there are Arbor-Plex ropes of bigger diameters which are intended for rigging, that of the climbing line is ½ inch or 12 mm. The rope is considered light as it weighs only 6.8 lbs for per 100 feet. In spite of being lightweight, this 12-strand, single braid rope is strong as it has a breaking strength of 6,000 lbs.
Arbor-Plex can hold knots pretty well because it stays flexible. Since it is lightweight, throwing it is easy. And because of the Duron II™ mantle, it will not get snagged on the tree branches. You can use Arbor-Plex even in wet weather as it is resistant to mildew. Apart from this, it is also resists chemicals and ultraviolet rays.