Nylon Three Strand rope. High strength with high energy absorbtion and elasticity. Meets or exceeds US Military specification MIL-DTL24050E. Specific gravity 1.14.
Three strand rope is pretty useful to boat builders as it can be easily spliced. Nylon has characteristics which make it ideal for dock and anchor lines. Those include shock absorbing qualities, good abrasion resistance, rot resistance, and resistance to oil, gasoline, and most chemicals as well as good resistance to UV rays. Grab a fid and a piece of three strand rope and make yourself a spliced eye. It's fun and not hard once you get the hang of it.
Sold by the foot.