YOU COULD TRY JUMPING INTO THE WATER, turning on your video camera, letting it run throughout your dive and adding a bit of music - but dont expect your audience to sit enthralled.
The amazing plankton drifting past as you descend into the depths might be a work of art to you, but your viewers are used to slick documentaries from the BBC and National Geographic. Unfair as it might seem, that is what your work will be judged against.
You too can make professional-looking underwater videos, but most of the crucial work will be done before you dip a toe in the water. Take as much or as little as you need from the following:

Pre-production means planning down to the minutest detail. You must always start with a story, however basic. It might be something as simple as a friends first dive, a scientific marine-life survey or exploration of a wreck site, but it must have a beginning, middle and end.
You need to set up a situation in which people want to find out what happens next. The beginning section should end with a turn of events that sends the story off in a different direction, usually about a quarter of the way through.
At its simplest, the first quarter might show preparation for a dive. The middle section should be about half the length of the whole programme. This is where things happen - the dive, the wreck exploration, the search for lost treasure. About three-quarters of the way through the total running time, the story needs to head for a conclusion. You find what you seek, or a rescue is carried out.
Writing this down as a script allows you to work out the logistics. If there is to be a voice-over narration, the script is often simply the voice-over, with the action made clear by the words. If there is little or no voice-over, you will need to describe the action.
Write the script in small chunks, numbering each section or paragraph, then turn it into a list of individual shots needed to tell the story. Your shot-list should indicate where they come in the script, the type (eg, above or below water) and a brief description of the action.
Drawing storyboards is impressive but really necessary only if you have to communicate your ideas to a large number of people, as on a feature film.
Now work out a practical filming schedule. Film-making is a time-consuming process, but under water the constraints of decompression, temperature and air supply all affect the planning of your shoot.
You dont have to film everything in chronological order. You will inevitably have to repeat shots a number of times to get them right, so plan for all those required at a certain depth or location to be completed at the same time. This will reduce the number of dives needed to achieve them.
Write all this down as a shooting schedule, with all the shots to be filmed on a single dive grouped together, along with a reference to their position in the script, and a brief description of the action.
Now consider the people, equipment and locations required. All plans must revolve around safety, so although the logistics will be more complex than usual, approach planning as you would for any dive, but with video-making as the dive objective.
Use only experienced divers. They will need to concentrate on more than their diving skills while under water.
Make sure everyone is well-briefed, so that there are no time-wasting misunderstandings later - you will often have to co-ordinate a number of people and actions at the same time. Assume that everything will take longer than anticipated, and make sure everyone knows they will be expected to stay until things are completed, safety permitting.
Film-making is often cold, boring, frustrating and tedious, particularly for those helping you out and not necessarily sharing your vision of an amazing movie.
Arrange the diving gear needed and select your locations. You might have little choice if the subject of the film is only at one location, but if youre making a general video about club-diving or training procedures, pick somewhere where the conditions are relatively easy.
You wont want to carry equipment over a great distance and should be able to exit the water easily to carry out repairs, or regroup to try other methods of achieving the shots. On a boat, most of these requirements should be satisfied anyway, but if on shore they are often overlooked.

Its time to commit your ideas to tape. Video cameras can be expensive, but you dont need the best equipment to make an entertaining programme, only competent technique and a little imagination. However, the type of camera will determine the type of housing and also the type of editing you will have to carry out later.
A Mini DV (Digital Video) camera is the ideal option. It is small and manageable, with Mini DV tapes the smallest on the market. Also, the DV format is compatible with non-linear editing systems, as seen on modern computers such as iMacs, G4s and PC-based platforms.
Other formats can be used with these systems but DV allows the footage to be loaded into the computer, edited and exported back to tape without any loss of quality. Non-linear editing systems also offer very advanced editing functions, and are the simplest to use.
DV cameras can be small but if you go too small, the camera and housing will have little mass in the water and will be harder to keep steady while swimming or holding a shot. Probably ideal, budget permitting, is the Sony VX1000. Its about to be superseded by the VX2000, but is perfectly adequate and has a number of housings available for it.
The best is made by Amphibico, rated to a depth of 100m and with 16 buttons which give full control over virtually all camera functions. This will be useful when you encounter difficult filming conditions, such as silhouettes and other lighting configurations, where control over the camera is vital to achieve an acceptable shot.
Other manufacturers such as Sea & Sea and Sting Ray also make housings for the VX1000. Housings for a whole range of smaller camcorders are manufactured by Gates, Guppy, Isotecnic, Seapro and Sony among others.
Whichever camera you buy, ensure that a housing is available that provides the functions you need at an affordable price. The choice is usually between those with electronic control, such as the Amphibico, and those that use physical control, such as rods. The former is sophisticated and allows more functions to be accessed, but can be temperamental and susceptible to moisture.
Underwater lights are incredibly expensive and do not illuminate a particularly large area, because of the absorption of light rays by the water. You can opt to position them either on the camera itself or have them hand-held by a buddy.
The size of mountable lights is limited, so the on-camera option is really suitable only for close-ups, or placing some fill light on a nearby object. Also, if the lights are too close to the lens they will produce back-scatter from particles in the water and reduce the effectiveness of the shot.
Its better to have your buddy carry a light for you, the problem then being to ensure that he or she keeps the light on the subject and follows it with you, if you are panning or swimming during the shot.
In many cases, the best option is to use filters. With the correct filter for the type of water colour and depth, you can achieve the same effect as lighting but far more evenly. In ideal conditions - clear, blue water, depth of between 5-10m - filters can put back all the colour absorbed by the water up to a specified distance from the camera. They also save the cost of lights, or problems with divers holding lights.
If you do decide on hand-held lights you need control of the buddy - you need communications. To get your work right means adjustments, repetition and telling people what they did wrong first time round, so that they get it right next time. Basic hand signals are not enough.
A wireless system such as the Buddy Phone allows free movement with no interference from cables. It can be problematic in a pool environment, when the transmissions bounce around the walls and disrupt the message, but in open water there is usually little problem. I have been able to cue actors into a shot from out of sight in a cave.
If you use comms, everyone needs a unit so that they can all hear your instructions. If divers without units are left out of your underwater briefings, the consequences will be inevitable.
On land, you can use a tripod to ensure that a camera remains steady. If you want to move it, a steadicam can be used.
Under water, your body becomes the steadicam. You must run a fine line between using the buoyancy in your BC, your breathing, and small adjustments of your fins to achieve the camera moves needed. This can be practised on any dive, using a buddy as a subject. After all, one of the advantages of videotape over film is that it is cheap and can be recorded over.
Film-making is the art of compromise. Dont be afraid to make your stars repeat an action until you are satisfied. It might not be their fault for fluffing the shot, you could have breathed out at the wrong moment, swum into an obstruction, or had any number of technical problems, but keep going till you get it right.
Try not to move the camera around too much. Panning is necessary only when you have something interesting to pan from and to. Too much can make people seasick! Avoid zooms, too. Zooming though any body of water with particles in will condense them in the shot, reducing quality and clarity.
Far more professional is to move in or out with the whole camera, relatively easy once you have mastered your movement in the water. It is easier to keep steady than on dry land but you can always take a tripod down, for macro and general close-ups.
Set up your shots carefully and see that the action is not confusing. Make sure the background is interesting but not distracting. Start by taking a master shot, or wide shot of the action, to tell the story you want to tell.
Next, shoot some inserts, or cutaways. If youre shooting a buddy pair ascending, for example, the master shot will show just that, while the cutaways might include a close-up of a BC inflator being pressed, a dump-valve being vented, or hand signals.
These can be cut into the master shot to show more clearly what is going on. It also makes the sequence more interesting - telling a story.
Covering the action from different angles allows you to cut, halfway through a scene, to the continuing action from a different perspective.
Again, this makes the action more interesting, but do ensure that your artists perform the action exactly the same each time, or some laughable moments will result.
If you have planned well, managed to control events and had luck on your side, youll be able to shout: Its a wrap! at the end of the day, and be well satisfied with your achievements. Now comes the tricky bit.

The project will fly or fall at the post-production stage. Your shots should be close to your original script and shot-list, but inevitably there will have been changes. You will have found things that were more interesting, and have missed some shots because of weather, time, etc. You should also have plenty of coverage - shots from different angles and cutaways. Deciding what goes where is always nerve-wracking.
With a simple camera-to-video editing system you plug your camera into a video recorder, press play on the camera and record on the video at the relevant point, and build the shots up. This is incredibly painstaking, and inserting a shot into a completed section later can be tricky. There is scope for things to go horribly wrong.
Try to get hold of a computer system instead. These days they are relatively cheap for what they do, and will make your life far easier.
You can change your mind more readily and try out different ideas.
Editing the programme requires the same decisions whether you use a camera-to-video editing system or computer system, but I will assume you are using the latter. Start by looking through all your footage to check that you have the shots you need and that they have turned out as planned.
The most tedious part of the exercise is logging the footage, but it is easier if the camera is one that lays time code onto the tape. This is not simply the hour, day and date, as displayed by cheaper camcorders, but specific data - the time code of every frame. This stays locked to the frame when you remove the tape and makes it easy to return to a specific frame at any time.
Write down the time code at the beginning of every shot (you need only the beginning, as the end is the beginning of the next one). The best way to do this is to record your rushes (raw footage) onto VHS. Make sure the time code is displayed, and watch these to avoid damaging the master tapes.
Your completed tape log should also include a description of each shot, and possibly notes to say which shot of, say, four is the best. Now make an edit list, essentially the original shot-list but with the relevant time codes.
How simple the process is from here on depends on the sophistication of your editing system. If you have iMovie software on an iMac, you go to the relevant time code on the tape and import the movie onto the computer.
If you use Final Cut Pro on a Mac, EditD V on PC or Mac, Media 100 on the Mac or an advanced Avid system on PC or Mac, you set the computer to pick all the shots off any number of tapes and put them in the right order on the time line of the edit software.
The time line is a sequential representation of the shots on the screen. There will usually be one line for video, a couple for soundtracks, music, voice-over, effects, and another for special effects like transitions or slow motion.
Once all the footage is on the time line in the correct order, you need to tighten everything up by cutting and pasting, as on a word processor. You might need to add transitions between shots, or extend or shorten others to make the edit smoother. Its worth seeing that shots are slightly longer than needed when loading them in, to allow for trimming.
Check continuity between shots. Cutting from one angle to another only to find a persons arms, legs or gear in different positions can be very jarring. Just watch the underwater fight at the end of Thunderball. In one sequence Bond loses his mask and picks another off a dead diver, which is a different colour to his own. He continues fighting, then, a couple of shots later, turns up wearing the original-colour mask again!
Move the programme along at a brisk pace. You might like to watch every moment of a dive but others wont!
You often find you have one perfect shot that took you ages to achieve but which does not relate to the story. Dont weaken - leave it on your cutting-room floor, or computer trash basket.
Once happy with your sequences, add sound effects and music for that polished feel. Its easy to add a memorable Enya track to set off your underwater world, but remember that all music is copyright and you would not be allowed to use that for a home or club video.
If you want music that can be usedlegitimately, approach the Mechanical Copyright Protection Society (MCPS). You have to register to use its members music, but once you have, you can receive free CDs of library music of any description. You just pay for any you use.
You wont know if all your hard work has paid off until you screen it for the first time. With luck the event will be greeted with gasps of wonderment, but whatever the reception, treat any comments as constructive criticism. It will always happen - be prepared for it!

The Sony VX1000 is a good choice for underwater video-makers.
It fits inside the Amphibico housing, which is rated to 100m and has 16 buttons to allow close control of the camera.
The lights can be mounted directly on the camera
Precise buoyancy control is vital, using the BC and small fin movements to help the divers body form a built-in steady cam.
If within your budget, a Buddy-Phone makes it easier to keep in touch with the human members of your cast and crew
Filters can be used to achieve the same effect as lighting, but distributed more evenly
During post-production, a good computer system makes all the difference.