Considering that the line is used just as a guide from this cavern and is not supposed to be pulled, lines bigger than 1/16 to 1/8 inch diameter are not required and are usually too bulky to become used.
White nylon line is better because it is easily observable, keeps its strength in water, and doesn't float. You can look for the best cavern diving experience via various online sources.
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A few cavern divers prefer braided nylon line rather than twisted nylon line. since the braided line is slightly more abrasion-resistant. Whichever type of nylon you use, it ought to be unreeled occasionally and assessed for abrasion.
In the past individuals have tried to use different sorts of the lineup for cavern diving, with unsatisfactory results. Polypropylene lineup, for example, water-skiing tow rope, will float into the ceiling of the cavern, making following the lineup poisonous.
Also, it can steer away from the diver and withstand normal line-placement methods. Manilla hemp ropes, for example as clothesline and twine, not just float, but rust and may be broken.
Fishing line is much too small in diameter and under specific conditions could not be possible to view, presenting a serious entanglement hazard. Nylon parachute cord is also not a viable choice since it's very tough to cut, and this may pose a critical problem in a lineup entanglement.