Line Arrows are isosceles triangle shaped directional markers providing both a tactile and visual reference to indicate the path to the closest exit.

Dry cavers were using directional markers long before there were any cave divers. The early cave divers in Florida saw the benefit of these markers, and Lewis Holzendorf came up with the idea of folding a triangle of tape around the line to form an arrow. These tape arrows were called "Dorf" markers, in Lewis' honor. There were a couple of problems with tape arrows, however -- they slid along the line and were difficult to feel in a silt-out. Cave diving pioneer, Sheck Exley asked fellow diver, Forrest Wilson to lead a discussion group at a NSS workshop, to come up with an idea for a better arrow. Several ideas were tossed around and eventually, Forrest came up with the current design. They soon became very popular and Steve Hudson of PMI cave rope company asked Forrest's permission to mass produce the arrows for Dive Rite.