In Boy Scouts we would go camping by a small ravine, 100 feet across and a good 50 feet deep.
We worked on the pioneering merit badge one year.
Make a rope bridge to cross the ravine. The catch? We had to make all the rope on the spot.
1 inch rope was the goal. It worked. We used 1/8 inch sisal to make the rope.
The 3 rope bridge was left up for future campouts.
It lasted 4 years until someone vandalized it.
Fun times.
I do agree that a cable bridge would be best.