When you flick through dive magazines, I'm sure you've noticed lots of images with divers in them. Those images are often the ones that stand out the most, and for good reason too – using a diver as a model when you're shooting wide-angle can enhance a standard photo of a marine animal, or a reef scene. Adding a human element to the image, a model conveys our interaction with the underwater world, and helps the viewer to understand the relative scale of the scene, or animal.

Dive with a dedicated model as your buddy, ideally someone you are familiar with who's willing to spend their dive modeling for you while you boss them around, which might take some persuasion – I find the promise of “the drinks are on me” usually helps! Spontaneously using a random diver in your group as a model for a shot can be a problem, as they won't understand exactly the kind of shot you're going for. He or she wants to enjoy the dive too, and won't be happy if you waste his or her time, because while underwater photography is fascinating to us, trust me, it can bore the hell out of others! You need to have a bit of patience when using a model, and remember it won't necessarily be the model's fault if you don't get "the shot".

To get the very best out from your model, here are some useful tips to follow:

Planning. It helps to have prior knowledge of the dive site, and what marine life you can expect to shoot. Your model should be a competent diver with good buoyancy skills (no flailing arms or legs!), who can handle him- or herself comfortably in a current, on a wreck, or with larger animals such as sharks. Have a pre-dive briefing with your model about the specific shots you want to get, and go over any important hand signals you may use. Give your model a bright torch, which is some situations (for example, on a wreck) can make the diver stand out from the gloomy surroundings. For closer shots, a mask with a transparent skirt allows more light into the mask and the model's face to be seen more clearly, and make sure his or her mask is de-fogged thoroughly. After diving, if you intend to publish your images for commercial use, make sure your model signs a model release form.

Communication. This is the "master key" to success when using a model. You must give your model clear and straightforward hand signals, of which there can be many. Signals I would recommend using are:

(1) come closer / move back; (2) stop; (3) move up / down; (4) horizontal / vertical (body orientation); (5) face this way / face the other way; (6) keep legs straight; (7) swim slowly here / there; (8) repeat shot; (9) torch on / off; (10) point torch at me; (11) look at me / look at the subject / look over my shoulder

Eye contact. This is especially important when shooting marine animals. But when shooting divers, unless the diver is the sole subject of the image and you really don't want them to look at the camera, try and avoid these 'posing' shots. The majority of quality images of marine life and divers are those where the diver isn't looking into the camera. With a foreground subject such as a turtle resting on the reef, have your model look at the subject but face the camera so the light from your strobes still lights up their eyes through their mask. For even closer shots with a foreground subject, a model looking over your shoulder can work well – his or her eyes and face are more easily lit by your strobes, and in your image it can appear that they are actually looking at the subject.

Camera settings. Start your dive with general settings: 1/125 sec, f/8, ISO 200, and turn your strobes to a medium-high power. In deeper water or in low visibility, use a slower shutter speed (for example, 1/30 sec) to brighten up the surrounding water. In bright, shallow water, or if you're shooting upwards towards the sun, perhaps to capture your model's silhouette, then use a fast shutter speed and higher aperture (1/250 sec, f/11+). If one strobe is directed at your model and the other strobe at the subject, then they should be on different power settings. Camera and strobe settings obviously need to be changed for various conditions, or to achieve a certain effect, and you should gradually learn what to change and when.

Lighting. When your model is close to the camera, you need to light up his or her face and body. Angle your strobe(s) slightly outwards to spread the light, which will also reduce backscatter (particles), and minimize flash reflecting in your model's mask.

When your model is farther away in the background, concentrate on lighting your foreground subject evenly.

In shallow water with good natural light, shoot in manual white balance mode to bring out the rich, natural colour of the foreground. For example, a wide shot of a colourful coral reef with your model in the blue background will look much better with your white balance set manually, than without.

Composition. If your model is far from you, avoid shooting towards the reef/wall etc. so they don't blend into the background. Try to shoot away from the reef/wall if possible, and isolate the diver with blue water around them. Foreground subjects are the star of the show, so should fill more of your frame, and keep the background model away from the center, in one quarter of your frame.

Orientation. Signal your model in the background to orientate themselves vertically, or horizontal and facing sideways, and keeping their legs fairly straight, so their outline will be clearly visible as a "diver" in your image. (A horizontal diver in the background facing towards you is not a very recognizable shape and just a distracting "blob" in the frame).

If the model is much closer to the camera, they should be facing you at a slight angle, so you can just see their body and fins, and not side-on. For even closer shots, a head-on view can work well.

Up close, be aware your model could blink as you take a shot, so you should review each image to pick up on faults like this, so you can re-shoot.

A quick way to correct faults and get the perfect shot is to show your model the image on your camera after you've taken it, so they can see what the problem is and what they need to do to correct it.

Movement. Because your model has to breathe constantly, bubbles are inevitable and often they can ruin shots, so you may want to time your shot when they inhale. However when captured just right, a stream of bubbles from a diver can look great because it adds motion to a 'still' image of the liquid world we're in, and enhances the underwater feel to the viewer. Using a slower shutter speed will also help to achieve this.

The Model Touch. Take it from me – a really good underwater model is hard to come by! If you have a diver buddy who likes having their photo taken, teach them about underwater modelling, dive together often, and modelling will soon become second nature to them. A good bonus is a model who also understands some basics about underwater photography, especially composition.

In my opinion, female divers often look nicer as underwater models than men, as they are more likely to wear colourful dive kit such as pink/yellow/white fins and masks, etc., which can really make a diver stand out. A touch of waterproof mascara on the eyelashes will also make their eyes pop in those closer shots. Hair is another factor to consider, and long, light-coloured hair looks best – have them untie their hair and let it billow around, but current/surge can be a bother.

Shooting underwater with a model can result in some really interesting images that stand out above the rest. Your images will give non-diving viewers an alluring glimpse into what it’s like to be immersed in our underwater world, and perhaps inspire them to take up scuba diving and share our love for the oceans.

Christian Loader (30, UK) is a professional photographer for Scubazoo Images. He has worked extensively throughout SE Asia as an underwater videographer and photographer, and is currently based in Kota Kinabalu, Sabah, Malaysia.