If we're really talking strength to weight/size ratios, then I would recommend (once again) dacron 120 lb fishing or kite line. I can spool 100 feet on a tongue depressor along with a bunch of duct tape and electrical tape and keep that in a pocket or pouch with lots of room left over for other things.

Paracord makes superb shoe lacing.
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The ultimate result of shielding men from the effects of folly is to fill the world with fools.
-- Herbert Spencer, English Philosopher (1820-1903)