This thread is for knots that can be useful to us in spearfishing. Add your favorite knots.
Butterfly Knot
This knot makes fixed loops in a line without the need for a free end. I use it to put loops in my float line at fixed intervals, to secure the float line at a different lengths for diving in varying depths. I guess it can be used to do the same with an anchor line.
http://www.netknots.com/html/butterfly_knot.html