Well, I've been playing around more with the Nik Software Silver Efex, and processed this B&W (ok, technically sepia) of a nurse shark photo that I've shared previously.

Technical Data: Canon EOS 7D, Canon EF-S 18-55mm f/3.5-5.6 II at 18mm. 1/120 sec at f/11. ISO 640. Ikelite Housing and Port with dual Ikelite 161 Strobes in eTTL mode. Raw conversion and cropped in Adobe Camera Raw, B&W conversion in Nik Software Silver Efex.

I really like how this one turned out. You certainly wouldn't think of sepia when you think of underwater photography, but then again... maybe you should... sepia is produced from the ink of cuttlefish!

- Bill