Be careful in Black Sand

Just a quick not to let you all about the issues when diving on these critter rich volcanic black sand dive sites with your expensive camera gear and lamps!

In a lot of places you should be careful about laying your camera gear and lamps down on the sand. Volcanic is often magnetic and if your housing has any magnets within it, there is a big likelyhood that you may end up with a pile of tiny black sand particles around the area that ahs magnets!

I use a Hartenberger underwater lamp which has magnetic device for operating the lamp. After dives on black sand the switch is often covered in black sand and eventually starts to wear away the switch beneath if this is not cleaned regularly!

This could another topic, underwater lamps and which ones are best!

Graham

http://www.diving4images.com

It isn't necessary for the housing or attached strobes etc. to have magnets in them for this to be a problem. Any electric circuit (for example, the ones between your camera and strobes) will create magnetic fields. (Volcanic sand is made up of ash and/or broken down basalt, which is itself a composite rock made up of tiny crystals of feldspar, pyroxene, and olivine. The problem for us are black iron sulfides and pyrites that also make up part of the ash or basalt, and which are attracted to magnetic fields.)

And one doesn't avoid the risk by never laying the camera gear down on black sand. The biggest danger, IMHO, comes when one cannot resist the desire to shoot in shallow water affected by surge and surf, which pick up the volcanic sand and suspend it in the water column. For instance, shooting flame file shells or boxer crabs under the rocks in the shallows at Tulamben (or any dive at nearby Seraya when there are big waves).

It's a good idea to check and clean all accessible o-rings (body, port, and battery compartment o-rings on strobes, etc.), o-ring grooves after any dive on black sand, particularly if there was exposure to silty waters churned up by surf or whatever. And keep in mind that the tiny o-rings around buttons and controls are also a potential threat.

Frogfish