Bowline on a Bight
(Harness Rescue Knot)
If you have enough rope for the job, a bowline on a bight can make a quick rescue harness to get a hiker out of a jam. After the knot is tied, a person can put each leg through the loops formed and hold onto the standing part to use the knot as a rescue seat.
Double the rope up before beginning to tie the bowline
Make an overhand loop on the standing part of the rope
Pass the loop end of the rope through the overhand loop, reach your hand through the loop-end of the rope and pull the doubled-up standing part through. Cinch tight.