@RussellSawyer I suspect that the particular knot used to secure an Ursack  (or any container, for that matter) matters very little.  The critters most likely to attempt to get to the contents are more likely to chew through the cordage (especially if is salty, say from perspiration, etc) than to untie the knots.

Either a bowline or figure eight is a good secure knot, useful for many applications.

 

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