Ice cave group shot

My photo tour group and I photographed one of the highlights of our trip today. We entered a stunning ice cave along the southern coast of Iceland. It's called Crystal Cave because of its beauty, size, and remarkable contours of blue ice. What you see here is the participants in my photo tour shooting the mouth of the cave. This is a 7-frame HDR image at 1250 ISO. I used a tripod, of course, and I exposed this image with a Canon 15mm fisheye lens. There is no apparent distortion because the ice is so abstract that it's impossible to discern the exact shape of the walls and ceiling. I used a high ISO so when I made the sequence of shots, the shutter speeds would be relatively brief. This meant that movement of the people would be at a minimum. I used daylight white balance.