Reef Knot

For uniting the end of two ropes of similiar diametre, start the Reef Knot by crossing the ends, forming a simple overhand knot, then tying another reverse form of the overhand knot, so that both ropes emerge from the same side of the loops. Pull the two end at either side simultaneously to draw the knot together.

A flat knot, the Reef Knot is the solution where bulkiness in the rope join is undesirable.