When I first learned to dive, underwater navigation seemed slightly pointless — after all, I planned to always dive with a professional dive guide. Like algebra in high school, it seemed like something to learn in order to pass a test, which could then be promptly forgotten. It was only much later, when I found myself on a dive boat in Florida that expected buddy pairs to explore the reef without a guide that I realized the error of my ways. After a frustrating dive spent getting progressively more and more lost (and an endless surface swim back to the boat at the end), I decided it was time to address my negligence and learn how to use natural navigation underwater.
Using Natural Navigation Underwater
In doing so, I discovered that while a compass may be the most accurate method of finding one’s way around a reef, there is also much to be said for natural navigation. In some rare cases, natural navigation is of little use, for example when trying to find an isolated feature in an otherwise flat and barren expanse of sand. In those cases, compass skills are vital. However, often and with practice, it is possible to accurately navigate your way to and from a specific point by relying on clues provided by the underwater world. Here we’ll take a look at some of those clues, and how to interpret them.
Planning your dive
As with most things in diving, successful natural navigation begins before you even enter the water. The easiest way to interpret nature’s clues is to already be familiar with them, and to achieve that, you must know what to expect from your dive site before taking the plunge. In some instances, this may mean listening carefully to the dive briefing aboard your dive boat; in others, it may mean doing your own research and consulting dive site maps for guidance. If possible, try to sketch a basic map onto a dive slate before entering the water so that you have a reference even when other concerns (like maintaining buoyancy and checking depth and air pressure) cause you to become distracted underwater. You should make a note particularly of significant features — a reef wall, an archway, a sandy patch — and agree upon a plan with your buddy as to how you will navigate accordingly. Make sure to find out how deep these features are; otherwise, you could miss them despite swimming in the right direction. Find out about the current, too, and always plan to start your dive swimming against it so that you can return with it, assuming that your entry and exit point are the same.
Diving your plan
The first step to finding your way back to a specific point is being able to recognize it when you do. For this reason, it is important to take a moment to look around when you first descend, and make a note of standout features that will let you know you’ve returned to your entry point at the end of the dive. For obvious reasons, make sure these features are permanent, such as an oddly shaped boulder or a strange coral formation. As you move away from your entry point, remember your dive plan. If you decided to swim out with a wall on your left, and back with it on your right, do that. In the case of less obvious navigational markers, it’s a good idea to move from one recognizable feature to the next, i.e., from this coral bommie, to that rocky outcrop, to that sandy channel. Mark each one on your dive slate, along with the depth and an approximation of distance, which you can measure using kick cycles. In order to easily retrace your path, it’s a good idea to look back as you pass each marker and memorize its appearance from the opposite direction. Where possible, follow natural contours, such as walls, slopes or wrecks, as these will make retracing your steps even easier.
There are a series of other natural indicators than can be helpful when it comes to underwater orientation. Depth is usually reliable; in most cases, divers who find themselves swimming progressively deeper along the seafloor are moving away from the shore and out to sea. Conversely, if you’re trying to get closer to shore, particularly when shore diving rather than boat diving, following a sloping bottom upwards is usually a safe bet. There are exceptions, however: pinnacles or areas with little variation in depth can be misleading, and for this reason divers should be aware of a dive site’s depth contours before attempting to navigate it. Sand patterns are another helpful clue, since ripples usually — although not always — run parallel to shore, enabling divers to orient themselves with the land. In clear, shallow water, divers can also use the position of the sun and any shadows cast by it to determine direction, although this tactic is obviously more useful in the morning and afternoon than at midday. Ultimately, successful natural navigation is all about being aware; about making a conscious effort to absorb and memorize your surroundings. It may take some practice at first, but like every dive skill, it becomes easier in time. Keep a compass with you to help when natural clues cannot, and if you can combine both skills, you’ll never need to fear navigating for yourself.