At that crucial moment when you find yourself eye to eye with a whale shark, its nice to know that your camera system wont let you down.
But to be that confident, you have to work at it. Water, particularly salt water, is a hostile environment for mechanical equipment.
Amphibious cameras, housings and flashguns are designed to operate under these harsh conditions, but they will go on doing so only with regular TLC - tender loving care.
The same principles apply to mechanical cameras and housings as to the latest autofocus models, although for the latter even a minor flood is far more dangerous. Water and electronics do not mix.
Establish good basic procedures for every-dive maintenance, backed up by regular servicing, precautions in transit and on-site, and your system should last a lifetime.
Before the dive
More cameras and flashguns are flooded by inadequate or rushed preparation than by any O-ring or structural failure. Even the experts flood their equipment, usually because something has been overlooked in their haste to get wet.
Always allow time for preparations. Find a clean area, decide what lens and film combination to use, then run through a set of routine steps:
After the dive
This is when some of the worst damage can occur. As the water evaporates it leaves salt crystals that can cause corrosion, dry out O-rings and eventually result in leaks.
In tropical waters with high salinity, such as the Red Sea, the water evaporates quickly, leaving especially large, invasive crystals.
Soak the system in lukewarm fresh water for a while, then work the controls to ensure that all the salt is flushed out. Finish with a general rinse under running water before leaving to dry.
If immediate soaking is not practical, a quick rinse under running water should suffice until later.
If you are on an extended trip, going through this operation after each dive, it is still worth re-soaking all your gear when you return home. Water in rinse-buckets at dive centres or on live-aboards soon becomes contaminated with salt from other equipment.
Many photographers use their equipment in intensive bursts, such as a weeks live-aboard trip, or for a few months during summer. During these periods, pre- and post-dive maintenance is normally sufficient to keep systems up to scratch.
However, when you come to store the equipment away, or if it has been used regularly for some time, it is worth extending your maintenance procedures to ensure that everything works when next required:
If you use your camera system only occasionally, say for an annual overseas trip, you can probably restrict service intervals to 18 months or even two years. If you use it more frequently, an annual service is advisable.
Whether you have an amphibious camera or housed system, the objective is the same - to dismantle, clean and grease the O-rings and control shafts that are inaccessible during routine maintenance. If this is not done these areas will gradually dry out, or a build-up of salt crystals on shafts or under controls will eventually work past a seal and cause a flood.
Amateurs with reasonable manual skills, the correct tools and a handbook can strip and service equipment themselves, if they have the courage.
Handbooks tend to be written by independent photographers who have developed their own procedures, rather than by the manufacturers. Several excellent publications with procedures supported by illustrations and photographs are available for Nikonos and Sea & Sea amphibious camera-owners, and servicing kits are available from the manufacturer and specialist dealers. A Manual of Underwater Photography (De-Couet and Green), the Nikonos Book series (Jim and Cathy Church) and How To Use Sea & Sea (Joe Liburdi and Cara Sherman) all provide sufficient guidance.
If you own a housing, the prospect of a full strip-down and service is less daunting. Controls, shafts and O-rings are larger and more accessible, although you must take care not to break components while dismantling the housing.
Whether stripping a camera or housing, be methodical. As you strip a component, note all spring positions and the orientation of controls on shafts. Place parts into individual containers (ice-cube trays are ideal). Replace all accessible O-rings and clean and grease those that cannot be removed by coating the cleaned control shaft with grease and running it back and forth through the seal.
Occasionally you will encounter seized controls or attachments, especially where stainless steel or brass is mixed with aluminium. Freeing these by force will inevitably cause damage, but soaking parts in warm water with a little vinegar normally helps dissolve corrosion deposits. Apply WD40 or Plus Gas and let it penetrate.
A last resort is to apply a heatgun gently and try to free the parts as they expand. Dont try this anywhere near plastic parts or very fine control rods!
If the prospect of all this effort and responsibility fills you with horror, pack your kit and send it to a specialist service centre or dealer. A full service might seem expensive, but if it saves you from a flood it is money well spent.
Most service agents return the equipment pressure-tested and with a short-term guarantee that gives you time to test it before your next trip.
All your efforts will be wasted if your equipment is damaged in transit to that exotic location you have saved for months to afford. Use strong equipment cases with plenty of internal foam padding.
Injection-moulded resin cases, like those made by Pelican and Underwater Kinetics, are among the hardiest but aluminium and plastic are also suitable.
Wrap fragile items such as lenses individually in foam or felt to stop them chafing against other gear.
On aircraft it is best to carry expensive camera equipment as cabin baggage, but if size and weight regulations force you to consign it to the rigours of the hold, you cannot have enough padding around individual items.
Lock or padlock each case and add a luggage strap to each in case a hinge or latch should fail. Stickers identifying baggage as containing photographic equipment are not a good idea!
Whether your equipment travels in cabin or hold, never forget to remove at least one main O-ring from each camera, housing or flash gun. Even the cabin pressure will be slightly less than atmospheric pressure at sea level, and unless this differential is allowed to equalise in your equipment, small O-rings can be displaced by the now-higher pressure in your equipment.
Many photographers have thought their equipment cases pressure-proof because they had an O-ring in the lid, only to find their camera or flash flooding on the first dive as an unseen O-ring dislodges on a cable gland or control shaft.
Whether on your one-day dive excursion or that long-awaited live-aboard trip, you are likely to be joining a group with mixed interests, perhaps assisted by a crew with little appreciation of the fragility of your expensive camera equipment. Here are a few tips for a happy trip:
On a safari-style trip, such as those popular in the Red Sea, you must take extra precautions. There is almost always a breeze on the coast that will carry fine sand particles, so prepare your equipment inside your vehicle or a tent, on a clean surface.
Washing your equipment after a dive is even more important when you have sand as well as salt with which to contend. Fresh water is often at a premium on these trips, so make sure that there is sufficient allowance for photographers when you book.