Thanks Colin, illustrates the effect quite well. As my compact camera housing (Canon's for a G10) doesn't have any provision for fitting a filter, I may see if I can get some red glass and make something up myself. Though how to get red optical-quality glass? And what shade to get?

Harriette, the obvious question has to be - why don't you use your Nikon setup underwater? The D70 may not be state-of-the-art, but it's still no mean camera and will give you excellent pictures. Lots of people still use them. And (the most important point this) you already own it! Were your lens problems resolved, so you again have usable lenses?

If you don't want to use it and it is usable, I can suggest someone who'd be only too happy to use it underwater for you!