https://www.good.is/articles/the-perfect-people-to-repair-wind-turbines-rock-climbers
When wind turbines need maintenance or repairs, you want people who are comfortable working 300 feet above ground, hanging from a rope.
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https://expertclimbers.com/do-sharpies-or-markers-damage-soft-rock-climbing-gear/
No, there isn't any proof that sharpies or markers damage climbing gear. But there are reasons you might not want to use them on your ropes.
soft rockclimbing gearsharpiesmarkersdamage