Garden eels: are they cute little devils, or what If youre an underwater photographer you will definitely go for the second option, because garden eels are anything but cute when youre trying to sneak up on them for a picture.

One minute theyre sticking photogenically out of their seabed holes, wafting gently to and fro as they search the current for edible morsels. The next minute they know youve cocked your shutter, and theyre gone. And they stay gone until, well, until youre gone too.
What you need is an electronic garden eel-sensing device to attach to your camera while you leave it positioned over the creatures hidey-hole.
Well, dream on, because all I can come up with right now is a remotely controlled underwater cable release, knocked together from the back brakes of my sons bicycle. He can manage without for a while.
As you will see from the main picture, the shoe on top of a Nikonos III camera has been designed to hold a piece of aluminium or mild steel plate (although Nikon doesnt know it). Fit a suitably sized and shaped strip of plate into the shoe so that it projects a little way behind the camera body.
When you have taken the sharp edges off the plate to avoid lacerations, drill it twice and tap threads in the holes: one to screw the plate firmly on to the accessory shoe, the other to take the bicycle brake cable holder.
Next fit a piece of metal bent into an inverted-U on to the shutter release. You either have to make sure its a tight fit or tap and screw again. On top of this gizmo sits another bit of bike brake: a trapping screw to secure the inner core of the cable.
When you retreat to the far end of the cable and tug on the wire core, while holding the plastic sheathing in your other hand, you can activate the shutter release. The Nikonos III has the advantage of using the same action for winding and releasing, so you can even wind on remotely.
I suppose if you wanted sophistication you could commandeer the bikes handlebars, with the brake lever still in position, to cut out the two-handed operation required by a loose-ended cable.
With the remote release attached, the camera mounted on a miniature table tripod, and your flashguns anchored by belt weights, youre in business.
To ensure that the garden eel gets used to the contraption, leave it in position for a day or so over the creatures burrow. (If that doesnt sound like a good idea, leave a camera-like object instead. A brick will do: eels don't know much about cameras.)
Replace the brick with the real thing at least two hours before you plan to shoot. Then snorkel up to the cable, hugging the bottom and moving very slowly, and voilà! You catch your garden eel on film (right).
Next month: a self-releasing camera trap for tiger sharks, made from kitchen oddments!