My project might interest you because all the images were shot on a Pentax K10D. The project is seeing a lot of interest from the UK photomags and is set to be published shortly.
HDR is used to good effect in this project. But the real challenge is accessing these caves safely using climbing and kayaking techniques. Many have never been photographed before.
You can read the full story here
Great Sea Caves of Antrim - Photography Portfolio 5 - County Antrim, Northern Ireland
Here's some examples
And here's some old etchings that inspired the project
Andy
www.skyandstone.com