This is a simple harness that is ideal for confidence roping when out on the hills, it also makes a good improvised harness for rescue situations that is a lot safe than non adjustable loop of rope, where the victim may slip out of.
Once tied, the rope be flaked into a dry bag with the loop easily accessible, ready in case it is needed.
Step 1: Stopper Knot
It is basically a corkscrew knot (with two twists), barrel knot, or one half of a double fishermans knot, depending on what you want to call it.
Step 2: Sliding Knot
You end up with a loop that can be slid open, stepped into, then slid closed up to the stopper knot, creating a secure fit.
It might be worth readjusting the stopper knot at this point, so that you get a snug, but not to tight fit.