Cave divers have a secret code… well, according to a non-cave-diving buddy we do. And perhaps she’s right; we do have a few odd hand-signals that are specific to cave diving.
What I did not mention to her when explaining the peculiarities of “ I’m Stuck,” “Changing Second Stages,” “Tangled in Line,” and “Okay buddy, I’ll help yer, but you’re gonna owe me…” was that some of the basic signs we take for granted in North America, are not universal in every cave-diving community.
Double arrows indicating proximity to a jump / side passage is a good example. (See the photo below.) Outside of North Florida, this may or may not signal what it does here: time to tie in a jump spool, fix attendance cookies to the gold line, and “Let’s go roaming!”
What’s perhaps more baffling is that even in the North American cave diving community, there’s a general misunderstanding about what exactly is meant by another set of double arrows.
The picture below shows two directional arrows pointing in opposite directions. Similar but with a very significant difference… well different certainly… but how!?
Until recently, I thought it generally accepted that this particular configuration indicated the mid-point between two “Ends of Line.” But during the past month, diving various caves but none separated from another by more than a two-hour drive, I heard it referred several times as indicating a “Safe exit in either direction” or “The halfway point between two exits.”
While it’s a fact that an end of line — a break in the main line — is usually where the overhead has a hole in it and daylight streams into the blackness of the cave proper, that is absolutely NOT the same thing as a safe exit; and the difference is more than a question of semantics, with the potential for a bad day ahead for assuming it is.
So, lets think about why this is.
A cave diving team, unless one of them’s clairvoyant, can only be sure of one safe exit: the one they came in by. Everything else is a mystery, and in truth, in a few cases there’s no absolute guarantee that when they get back to the hole they came in by, it’ll still be passable. Perhaps the only sure bet is large, open caverns like the entrance to Jackson Blue Springs in Jackson County, on Florida’s panhandle.
Caves, and especially sinkholes, have a dynamic nature. A sinkhole that a diver could climb in and out of yesterday, may have suffered a mini-landslide overnight making it impassible today. A tree providing shade last week, may have had its root system undercut by yesterday morning’s downpour, and is now sitting in the sinkhole like Aunt Zenia’s potted aspidistra: short of digging out, there is simply no exit now. A rock may have fallen from the ceiling a few feet from the sinkhole blocking access with an immovable chunk of limestone and 40-million-year-old fossils.
So, that’s why it’s a little risky to assume the mid-point arrows indicate anything other than equal distance between two ends of the main line, and nothing more… at least that’s the case in North Florida.