Where am I
Are you one of those divers who gets hopelessly lost under water, and relies on others to find your way around No, of course youre not, but for all those who are, John Bantin has some advice

Why do divers leave their brains behind the moment they hit the water asked the deck-hand of the boat on which I was dive-guiding. I had given everyone the simple briefing to keep the reef wall to their left but, not unusually, the group had managed to split in two the moment they submerged, the splinter groups heading off in opposite directions.
I put it down to the fact that in the initial moments of hitting the water and swapping the two-dimensional world for the unfamiliar 3D world of the diver, some get disoriented while others simply follow on behind.
It doesnt matter how much diving you do, its always an unfamiliar world down there. Even when its gin-clear, it seems its only too easy to get lost.
Following someone else blindly is just not good enough.

behind you!
Underwater navigation is about getting to where you want to go and knowing how to get back should you need to.
In perfect conditions, thats a simple matter of watching where youre going and retracing your course, which often means keeping a look-out behind you as you progress, to see the view from the other direction.
depth guide
If the terrain is less dramatic, you might need to note the depth. This usually increases the further from shore you are, although not always. In this way, your computer or depth-gauge becomes a navigation instrument by indicating your exact position in the water column.
Noting depth changes is particularly useful when other reference methods are not available. Similarly the observation of bubbles - which, scientists have found, usually go up - can come in useful.

distorted signals
It can be difficult to use the sun as a point of reference unless you are diving early in the morning or late afternoon. Refraction through the surface can make it seem always to be directly overhead when it is not.
Currents can change direction during the period of the dive, not only relative to the underwater topography but also to your own direction.
Ripples in the sand caused by waves can be misleading too, if you are not familiar with the location. Despite what you might be told, note that they dont always run parallel to the shore.
right angles
Many years ago, in the clear waters of the Med, a diver who should have known better commented to me: Its amazing - just as were running low on air and need to surface, theres the boat, just where we left it!
Yes, its amazing what can be done with a compass and a simple rectangular course.
Later, as an instructor, I was equally amazed to see what other people managed to achieve, even with a simple reciprocal (there-and-back) course - total confusion.
If you swim approximately the same distance punctuated by three 90Â turns, it doesnt take genius to come up somewhere near the boat.
Of course, you have to add the information from the compass to that acquired by your eyes. It takes practice.

double attraction
Your compass works by pointing its needle either towards the planets magnetic north, or towards the nearest mass of ferrous metal, or else it combines the two effects.
Thats why its best to hold it squarely in front of you, away from your steel tank and other equipment.
You need to use two hands to do this properly, unless you are particularly proficient .
Using a compass on your wrist makes it almost impossible to follow the direction-of-swim arrow or lubber-line precisely.

dont compass-watch
If you spend your dive slavishly studying the compass, you will see precious little else. Make a note of the heading you require with the aid of the compass bezel ring, then take a bearing on the furthest visible reference point.
It might be a rock, a coral head or even some weed - only the most unadventurous fish make good reference points.
Enjoy your dive, heading in the general direction of that reference point, and take a bearing on the next.

swinging free
Be sure that your compass needle or disc can swing freely. I once experienced a compass that was fine in the air but jammed under water because of the pressure. It was depressing to come up at night in the Red Sea to find that the boat was a brightly lit speck in the distance.
follow the light
Usually the crew of a vessel deploys either a bright light or a flashing beacon beneath it during a night dive. This makes a good reference point.
If you lose direct sight of the light because it becomes obscured by, say, a coral head, occlude your own lamp by holding it against your body.
Once your eyes are accustomed to the darkness, you will often see the haze that surrounds the light source, caused by light reflecting off detritus in the water. This will give you a general direction.

out of the labyrinth
Keeping your compass away from your tank is one thing. When diving on a steel wreck, you will have to use another method to find your way.
You could rely on your eyes, but wrecks can be confusing, and many of us would get lost on a fully functioning Channel ferry. If you are diving in home waters, your eyesight might be of little use anyway.
Here Theseus comes to our rescue from Greek mythology. He, as you might remember, found his way into the Labyrinth in Crete, slew the Minotaur and found his way out again because he took the precaution of unravelling a ball of string as he went.
With luck, you will have found the wreck or seabed at the bottom of the shotline, and this represents the first part of the unravelled string and marks the most direct route to the surface - where the boat coxn expects you to come up.
To find your way back to the shot, securely clip your bottom-winder line to it before setting off. When the time comes, follow your line back to the source, winding it in as you go.
Line-laying is an art and few do it well. You need to belay the line by tying it off at convenient points as you progress. Trained cave-divers do this, connecting several main lines together and spurring off for local exploration with shorter ones on smaller reels.
If you spur off a main line that has been pre-laid, you need to know which way is out when you return to it. This is when direction arrows fitted to the line become life-savers.
If things get stirred up, as they do, you will need to feel your way out. Losing a grip on the line is a serious matter, as is disconnecting another divers bottom line, but it happens.
Thats why its never a good idea to pull it or put pressure on it as you use it. If disconnected, it will, with luck, lie where it dropped, and you will still be able to follow it back to near where you started.

ultrasound advice
Ultrasonic navigation devices involve a beacon and a receiver. The beacon gives out a signal and the receiver indicates the direction from which it is coming.
Ultrasonics work well in poor viz but, remember, they still depend on line of sight. If there is an obstruction between the two units, the games up.
Knowing when and how to deploy a beacon is essential. It is not a magic solution to navigation and there is always the risk that another diver will find your expensive beacon apparently abandoned and remove it.
A compass is a cheap, surprisingly reliable item. Make sure you know how to use one, by referring to your training manual and practising. Learn to trust it.
We have dealt with finding your way back to where you started, but a strong current can throw out all your best-laid navigation plans.
Dont kid yourself that you can vector a course accurately while swimming. Navigate your way to the surface at the end of the dive and be ready with a good way to signal to the people in the boat that you are there. Thats another story.

Start a Forum discussion on this topic