WHAT WAS YOUR MOST MEMORABLE diving experience? The interaction with a giant whale shark? Finally stumbling across that wreck you had spent years looking for? Your first moment discovering the freedom of neutral buoyancy?
If you are an underwater photographer and have spent a lot of money on a camera only to see it flooded, its most likely the moment you watched in horror as big globs of air belched out from your underwater housing. It's an image that stays with you for the rest of your life!
I remember hurriedly ripping a wet camera from its housing and trying to decide whether to try to save that or the wooden boat I was on, because it was in serious danger of catching fire from the lithium batteries that seawater had turned into an incendiary device.
This is why you so often see divers swimming along with empty housings, or divers gingerly dipping an empty housing on the end of a rope into deep water. Once bitten, twice shy - and, with the rising cost of digital equipment, we are all getting very shy.
Even then, once tested, the housing still has to be reopened and the camera mounted. This brings with it all the hazards of crimped O-rings, or that rogue bit of fluff from a towel that can make the difference between lots of successful underwater pictures and a lump of wet junk.

LEAK DETECTORS ARE NOT WHAT they're cracked up to be. They might warn you if you get a few tears of water in with your camera, but if you're a long way from the surface when that happens, there will be a lot more tears besides.
Then there is the extra cost of replacing the leak sensor once youve rinsed the housing with fresh water and chucked the camera in the bin.
So how can we know if our housing is going to keep our precious electronic camera dry?
We cant, we simply hedge our bets - unless, that is, we are Hugyfot housing owners.
Hugyfot camera housings come from the same people in Belgium that make GreenForce lights. They generously sent me one for use with my Nikon D200 camera.
Yes, I know its obsolete - please dont remind me. Ive already ordered my D400 for when Nikon decides to upgrade the D300.
Hugyfot housing-owners now have the option of using the HugyCheck system. Its an option on which only a big gambler would choose to pass.
It does mean having an extra hole through the bulkhead, or a manifold fitted to an existing flash lead connection port - and this, it could be contended, makes for one more potential failure point - but its usually the main O-ring of the lens port on which we photographers foul up.

THE HUGYCHECK COMES WITH SOPHISTICATED electronics and a pressure-sensor. These are installed within the housing, and connected to the unit that interfaces the camera synch on the hot-shoes with the housing synchro port.
Once a battery is fitted, the pressure-sensor reads that you have a bar of pressure or thereabouts, equating to normal air pressure, within the housing.
A red LED also flashes to tell you this. With older housings, you can see this in the info window on top. With the latest housings, you can see it through the window just above the viewfinder.
Now comes the clever bit. Seal up the housing as usual, ensuring that the O-rings are clean and properly lubricated, and sitting where they should be in their grooves.
Undo the HugyCheck port plug and insert the mini vacuum pump provided.
Squirt the motor until the red LED stops flashing, and a green one replaces it.
The green LED indicates that there is reduced air pressure within the housing. The O-rings should all have pulled in nicely. The green LED continues to blink.
If the housing is going to leak, at this point harmless air will seep in, activating the red LED again. Green is good. Do this about 30 minutes before diving and, if you still have the blinking green, you can be sure that your housing is not going to let you down.
I was bemused to discover that the bolts that clamp the two halves of the clamshell together were quite loose after I had used the vacuum pump. It also proved impossible to break the two halves apart.
In fact you need to unscrew the Hugycheck port from the bulkhead after diving in order to release air at ambient pressure into the housing to be able to access the camera.
The latest Nikon D300 and Canon 40D housings come with three bulkhead connectors. As the HugyCheck system uses a bulkhead connector manifolded onto a standard Nikonos flash connector on the older Hugyfot D200 housing I tried, I wonder if this system with its electronics will ever be made available to those of us who have committed our savings to a camera housing of another brand.
In the meantime, it will be Hugyfot owners wearing the smug expressions.
If you Google HugyCheck it will ask you if you meant Huge Check. This seems portentous. Housings for digital SLRs are expensive, and the aluminium Hugyfot complete with appropriate lens ports and, perhaps, a rotating 45° viewfinder will set you back a tidy sum.
Perhaps Ill wait for my next-generation DSLR first.