Double Fisherman’s Knot.
The double fisherman’s knot, like a sheet bend, can be used to join two lines together. That is in fact where this knot gets its name – its a favourite of fishermen who need to join together two fishing lines
Like the buntline and anchor, the double fisherman’s knot works awesomely as an end-line knot when using the split-tail climbing system.
One of my favourite tree climbing knots – check out the step by step slide show below for tying method.