The Bowline is the king of knots. Sailors, foresters, cowboys and mountain climbers all lay claim to this knot. The great thing about this knot is that you can pull a tank out of a mud hole and still be able to take the knot apart with your fingers.
It should be tied with a stopper knot, overhand or such. Also never use this as a method of tieing in to your harness for climbing. It is not easy to tell if it is done correctly and because it does not tighten up it can come undone. In fact it is safe to say that more then 90% of knot failures at the harness is because this knot came undone. Y