3 REASONS WHY GUIDELINES SHOULD NOT BE ON CAVE MAPS, AND WHY I CHOSE TO IGNORE THEM.

• by Rory O’Keefe, November 8, 2022

I recently published a map of cenote Dos Palmas, and I made the unusual decision to include the guidelines. Most cave cartographers would consider this to be a deadly sin, while most divers seem to love it.

Personally, I lean towards the latter though I won't deny the reasons to exclude the lines are completely valid!

1. DIVERS IGNORE THE CAVE AND USE ONLY THE LINES.

Guidelines are normally removed from cave maps to prevent divers from ignoring the cave and planning solely off of the line survey. To use a map without the guidelines you are forced to use your compass, anticipate tunnel intersections, keep track of distances, and look for other references such as noticeable depth changes, restrictions, or passage shapes that are shown in the cross-sections.

When it comes to planning dives using a guideline map, I'm sure many divers have been guilty of planning something along the lines of, “Right, we're going to start on this line, take the third jump left, swim a bit, and then drop our stage at the T-intersection…” That “swim a bit” part might go through 300 meters of low-ceiling passage full of delicate, unbroken, speleothems, but they’ll find that out when they get there….

This type of planning definitely happens, and while I'd like to hope that most divers learn from their mistake, cartographers take notice of the damage done, and I wouldn't blame anyone for seeing this as a good reason for removing the guidelines from a map.

Knowing this, you might ask why I still chose to include the guidelines on my map of cenote Dos Palmas?

A good navigational map should contain all of the information necessary that a diver needs to get from Point A to Point B, without additional explanation or briefing from someone already knowledgeable of the cave.

While proper cave diving practice teaches us to “dive the cave, not the line,” the guidelines still play a major role in safe cave diving. The lines physically exist in the cave, and divers use them. Having foreknowledge of where the guidelines begin, and where they go, enables a diver to better focus their planning time on taking notes of actual cave features and environmental conditions that they should expect to see.

2. THE LINES WILL CHANGE.

Another common reason to exclude the guidelines from a cave map is that the lines will change over time, making the map inaccurate. This is a valid point and it is the responsibility of the cartographer to address this issue in the notes section of a map that features the guidelines.

A guideline change can certainly cause some confusion, but there is no realistic scenario that this should result in anything more than an inconvenience to divers following safe cave diving practices.

The worst-case scenario of an unexpected change in the line routing should be nothing more than a diver having to repeat their dive to find the correct passage based on their new knowledge of the cave. Divers who encounter a change in the guidelines should contact the cartographer to report the change, as the cartographer may wish to publish an updated edition of the map in the future.

The majority of the work involved with mapping underwater caves lies in the sketching of the passage - the line survey is done quickly, and by far the easiest part of a project. With the cave passage already mapped, a cartographer can feasibly spend a weekend scootering the cave while taking note of the new line routing to update their map.

It is also interesting to note that because the cave walls and features should remain the same, a survey-update can technically be done by any cave diver capable of surveying. This means that anyone with a digital copy of the map can continue to update the cartographer's work long after they have passed.

While it is unrealistic to expect cartographers to frequently update their maps, a time-frame of approximately 10 years is very achievable. This also provides the cartographer an opportunity to add any new passages that may have been discovered during that time-frame, or make other minor improvements to the map.

3. THE MAP ISN'T EXCLUSIVELY FOR DIVERS.

One final point to consider is the intended purpose of the map. Remember: not all maps are made strictly for diver navigation!

There is only so much available space for details on a cave map, and a cartographer needs to focus on the details relevant to the type of map they are making. For example, some maps are made to show the geological features of a cave while others might be made to document archaeological sites. Divers can still make use of these alternate styles of maps to plan a dive - a practiced cave diver can eventually learn to navigate a cave using a detailed geological map just as well as they could with a guideline map. However, the diver will have to make a few dives to first learn the general layout of the guidelines to build a basic knowledge of where they are on the map.

A navigation-specific map should be designed to teach a reader the necessary information they need to understand the cave before ever reaching the entrance, and the general layout of the guidelines is an important factor in meeting that criteria.

It is ultimately up to the cartographer whether to include the lines, and I hope that I have outlined some of the reasoning behind why cartographers might choose to exclude the cave lines from a map.

Remember, it is the cartographer's job to map the cave, and the divers' job to use that map responsibly.