Underwater Navigation 101: How to Navigate Underwater
Finding your way underwater can be tricky, right?
So navigation skills are key to a successful dive.
Learn to cover the basics here.
One of the elements of both entry-level dive and advanced dive courses that challenge most divers is the navigation.
There are a number of reasons for this. The main one being that because we don’t have the visibility underwater that we do on dry land, using visual references can only do so much.
So learning to navigate properly is a critical skill to learn to become a safe and successful diver.
Getting lost underwater
The first and most important thing to understand is that navigation underwater is quite a bit more challenging than on land.
Relying on your sense of direction will most likely just get you into trouble.
In fact, there are studies that seem to indicate that there is no such thing as a “sense of direction”. But rather that people who are good at finding their way subconsciously make note of navigational landmarks such as buildings, trees, the orientation of the sun, etc.
Underwater, these landmarks are few and far between, plus, visibility is often limited, making just swimming in a straight line a challenge.
Very few people, if any, can successfully maintain a straight course blindfolded (this was even confirmed on the TV show Mythbusters), but will deviate from the course quite severely.
So start by accepting that if you don’t actively navigate, you’ll get lost.
Divers natural navigation
So what to do? The first thing you can do is to use natural navigation. Natural navigation is defined as navigation using naturally occurring elements in your surroundings to indicate direction.
You can also read our guide on natural navigation.
In diving, this could be using the direction of the waves to find your way back to shore (along shorelines, waves will usually move in the direction of the shore), or using the contours of the bottom to make sure you’re moving in the right direction.
It can something be as simple as swimming with a reef on your right side on the way out, and on the left on the way back (or vice versa, of course). So anytime you’re not using instruments to navigate, you’re doing natural navigation.
Compass navigation underwater
If you don’t have the advantage of landmarks or other naturally occurring phenomena to aid your navigation, or you don’t know an area well enough to find your way with natural navigation, a compass is the right tool to use.
Compasses are delightfully simple, and have been made the same way for centuries: a magnetized piece of metal is suspended in a liquid, and due to the Earth’s magnetic poles, that piece of metal will always alight itself in a north/south directionality.
This allows you to orientate yourself and make sure you stay on course.
Use simple underwater compass navigation
The easiest form of navigation is a straight there-and-back approach.
You swim out in one direction, and back the way you came. For this, simply make note of the direction in which you need to swim and maintain your bearing using the compass.
Once it is time to return, just rotate 180 degrees to go back the way you came.
Divers advanced compass navigation
If your dive plan doesn’t allow for something that simple, the navigation becomes a bit trickier.
A square pattern is fairly straight forward, you simply need to turn 90 degrees each time to come back to more or less the area you started out from. The trick is to make sure each length is approximately the same length.
Triangles require more math, as you need to add 120 degrees for each turn. Some dives, such as wreck dives, may require you to follow quite specific instructions. Such as “follow heading 120 for approximately 10 minutes, turn to heading 240 until you reach a depth of 30 meters/100 feet, then turn to heading 200 until you reach the wreck”.
Remembering details like that can get tricky, but a simple writing slate or wetnotes will do the trick for that.
Tips and tricks for using a compass underwater
Always hold the compass level. Tilting the compass will most likely make the compass rose (the thing that turns inside it) stick, so it doesn’t rotate. Meaning you could deviate from your course without knowing it.
Keep it as far away as possible from metal. Metal messes with the magnetism in the compass, potentially giving you a false reading.
Don’t use if there’s a bubble in it. Bubbles can also make the compass rose stick.
Check it often. Again, don’t rely on your sense of direction. Just because you’ve read your compass once doesn’t mean you can ignore for as long as you “just have to go straight”. Check frequently to make sure you’re on course and make corrections if you’re not.
Advanced navigators will use a combination of techniques to find their way. These include:
- A compass to maintain directional awareness
- Natural features for waypoints or markers
- Currents and sunlight
- Depth is also useful
If you know the wreck you’re looking for is at 60 feet (20 meters), keeping an eye on your depth gauge will let you know when you’re in the area. If you’re heading back to shore, you should be heading for shallower water.
If your depth gauge tells you you’re in fact going deeper, you’re heading the wrong way.
How are your underwater navigation skills?
Do you have mad skills in navigating and use a compass on all your dives or are you a beginner at this important dive skill? We are always interested in knowing your take on underwater navigation: do you love or hate it? And do you have any great UW navigation tips you could share with the other divers?