Wrecks are great because they have many areas of strong contrast, and the black and white technique helps to emphasize shapes, structures, textures and tonality. Black and white also helps convey a feeling of melancholy with wrecks that have a significant history, or sunk tragically with loss of life. As a finishing touch when editing, adding grain or noise to the image gives a more historic, "decaying" look.

Nikon D300, Tokina 10-17mm, 1/30s, f5, ISO200

Christian Loader/Scubazoo

The black and white technique emphasizes shapes and patterns. Here, there's good contrast between the dark rays and the light sand, while the shape of the rays is striking to the viewer. The shadows of the rays, the dappled sunlight, and the pattern of ripples in the light sand adds some depth to what would have been a fairly flat image.

Nikon D2X, Tokina 10-17mm, 1/200s, f18, ISO250

Adam Broadbent/Scubazoo

Using just Adobe Photoshop alone, there are many different ways to convert color images to black and white. Adobe Lightroom and Apple Aperture are also fantastic photo editing programs that allow very easy conversion of images to black and white. All of these programs have plugins or presets for various black and white styles at the simple touch of a button. Silver Efex Pro is a program specifically for black and white photography, and comes highly recommended by the pros.

Nikon D2Xs, Tokina 10-17mm, 1/160s, f7.1, ISO100

Jason Isley/Scubazoo

Distracting, cluttered backgrounds with lots of detail are generally a bad idea for black and white images. In this shot however, although there's lots of detail in the sunlight ripples on the seabed, the background itself is clean and simple. Light, sandy seabeds reflect sunlight, increasing contrast with darker subjects, and make great backgrounds.

Nikon D2X, Tokina 10-17mm, 1/200s, f16, ISO100

Adam Broadbent/Scubazoo

By increasing the contrast and adjusting the tone curve with editing software such as Lightroom, the background blue water is rendered black, resulting in a more striking image.

Nikon D300, Nikon 24-70mm, 1/160s, f6.3, ISO200

Christian Loader/Scubazoo

Be careful when choosing macro images or subjects for a black and white photo, as many macro subjects are very colorful and often look much better in color than black and white. This original image was just black and orange, and still looked nice in my opinion converted to black and white. Had there been more colors in the original image, I would have left it alone.

Nikon D300, Nikon 105mm macro, 1/80s, f13, ISO100.

Christian Loader/Scubazoo

Look out for subjects with good tonal contrast, such as those with dark and light stripes. This Banded Sea Snake is a perfect example - shot in the late-afternoon at a downward angle to give a very dark background.

Nikon D300, Nikon 60mm macro, 1/250s, f4.5, ISO125

Christian Loader/Scubazoo

Shooting large animals such as this, you need to get as close as possible - or let it come close to you! The darker parts of this Humpback contrast nicely with the gray background water. If the Humpback was further away, it could get 'lost' in the gray background. By getting a close-up shot like this, the contrast around the eye makes it pop, and the eye-contact in this image really captivates the viewer.

Nikon D2X, Tokina 10-17mm, 1/125s, f4, ISO100

Jason Isley/Scubazoo

Shooting with only natural (ambient) light underwater generally gives a nicer, more organic result compared to using artificial strobe light. Here, sharpness and tonal contrasts complete the image - using a very low f-stop, with the Mimic Octopus' striped arms.

Nikon D300, Nikon 50mm, 1/1600s, f1.4, ISO100

Christian Loader/Scubazoo

Simple subjects and a simple composition make the best black and white underwater images.

Nikon D300, Tokina 10-17mm, 1/160s, f14, ISO200

Christian Loader/Scubazoo

Switch your camera to actually shoot in black and white (taking a RAW colour image, as well as a black and white JPEG). By thinking and shooting in black and white, adjust your settings based solely on the black, white, and gray tones displayed on your camera's LCD screen. Doing the occasional black and white dive will help to enhance your understanding of light - the key element in underwater photography.

Nikon D300, Tokina 10-17mm, 1/125s, f8, ISO200

Christian Loader/Scubazoo

Black and white images of large schools of fish such as this result in many different shades of gray, which compliment the highlights throughout the image, as well as the dark water below. A carefully-selected white bikini for the model, makes her really stand out too.

Nikon D800, Tokina 10-17mm, 1/100s, f10, ISO 250

Jason Isley/Scubazoo

For moody images such as this skeleton of a poor Green Turtle which drowned in a cave, black and white helps convey a sentimental feeling, or a feeling of loss to the viewer. This also applies with wrecks, and many conservation-style images such as a dead shark caught in a net for example.

Nikon D2Xs, Tokina 10-17mm, 1/125s, f11, ISO320

Christian Loader/Scubazoo

Another good example of a subject with good tonal contrast is this juvenile Barramundi, with its bright white body, and black spots. I shot this against black sand, which gave a very dark background (which had some distracting, messy bits to it). I cleaned the background up using the adjustment brush and spot removal tools in Adobe Lightroom.

Nikon D300, Nikon 105mm macro, 1/125s, f7.1, ISO160

Christian Loader/Scubazoo

'Tonal contrast' is one of the key aspects of black and white images - the contrast between dark and light areas. Silhouettes are a great example of tonal contrast, and make wonderful black and white images.

Nikon D300, Tokina 10-17mm, 1/250s, f11, ISO200

Christian Loader/Scubazoo