The safe way to make a visual jump when cave diving… Don’t
Every open-water diver knows that the first rule of scuba is: don’t hold your breath. Always have plenty of something to breathe, so you don’t have to hold your breath. In essence, the same basic advice, but more detailed.
Cavern and cave divers have rules too; most of them are adapted from (and piled on top of) those from all the prerequisite courses.
But some are unique to the overhead environment. The first is: Always maintain contact with a continuous line to a known exit. For non-overhead environment divers, here’s a brief explanation of what that means.
You may already know that cavern and cave divers follow a piece of string – a guideline – when they’re swimming around. In most cases, certainly in the caverns and caves publicly listed as potential dive sites, this permanent guideline is already installed. Its upkeep and maintenance are usually handled by local instructors or an organization such as Creed.
Some folks refer to these prepared and monitored sites as ‘tourist caves.’ That’s not a put-down and certainly is not meant to trivialize the potential challenges these dive sites present. It simply means they have been explored and are somewhat ‘sanitized.’ Perhaps Fit for Purpose is a better way to explain it. The cavern or cave has been prepared for properly certified and experienced divers, rather than explorers.
In these caverns and caves, if visitors follow the line (and maintain visual contact with it), by default, they’ll always know the way back the way they came in and to the exit.
That’s the Coles Notes version, of course. There is a lot more to cavern and cave diving, but this is navigation 101.
Cavern dives are restricted to the ‘daylight zone.’ Daylight is the primary light source for these dives, and because of this, the primary line and the exit should always be in sight. In a bid to keep things simple, the permanent line in a cavern is often thicker than the line inside the cave and often gold or yellow. Inside the cave – beyond the daylight zone – the line is usually white.
Very few caves are like drainpipes: a simple tunnel. A cave typically has more than one passage and will be more like a Swiss cheese or a true labyrinth: complex and potentially confusing.
To illustrate the point, here’s a portion of a map showing the layout of a Mexican cave. This is a section of a typical ’tourist’ cave in the Yucatan. The blue-tinted portion is the section of the cave which is water-filled. And each of these passages has a permanent line installed. The layout and intricacies of the permanent lines installed in this network of passages and tunnels follow strict guidelines. For example, to help navigation and avoid confusion, one route is designated the “main line.’ It’s usually the one that’s the longest route in the system and the one that passes through the most interesting scenery.
Sometimes, but not always, the main line will be slightly thicker than the lines installed in other passages. Jumps are another name for these side tunnels. To help with navigation and to help divers keep track of where they are in the cave – since one piece of string looks very much like any other piece of string – there is a break in the installed line: a gap between the main line and the line in the side tunnel. This means that divers must jump from one line to the other, hence the name.
But there is a complication. Because there’s a cave diving rule about ’maintaining a continuous line…‘ etc., etc., making the jump from the mainline to a side passage, or any jump from one line to another, divers must install a temporary line leading from where they are to where they want to go.
Doing this requires a few steps and a small jump spool or jump reel. The whole process of installing this temporary line and marking it with personalized line markers takes only a couple of minutes, and a couple more when it’s taken out as divers pass by on their way back to the exit at the end of their dive.
Installing lines is part of the fun of cave diving. Doing it well is satisfying. Looking back on a jump line you and your teammates have just installed, seeing that no silt was disturbed and that the line is tight, well-placed, and correct is reassuring.
And of course, it’s a huge part of being safe and being sure there’s a breadcrumb trail to get you back home.
Quite remarkably, there are divers who promote doing so-called visual jumps. When asked, they’ll tell you that when the gap between two lines is only a couple of metres (a body length or thereabouts), it’s not worth the bother of installing a gap reel and the required line marker pointing the way out. It’s “a waste of time,” and it’s better to “push on.”
Can you think of a scenario in which not following the first rule of cave diving could cause a problem?
Perhaps this is not the time to introduce Sheck Exley or to explain why he made up that rule back in the early days of cave-diver training. We could discuss the normalization of deviance and how much trouble it can cause a diver. But instead, maybe it’s enough to say, the only safe way to ignore a basic rule is not to resist the temptation to do it. And in the end, to explain that there is no safe way to do a visual jump. Don’t do it.