Ice Caves of Iceland
One of the most exciting and terrifying experiences I have ever had was exploring an ice cave with a mountain guide in a remote area of Folljokull, Iceland this past January.
A few things that our mountain guide taught us is that ice caves are temporary structures that appear at the edge of glaciers. The ice is centuries old and is highly pressurized and contains almost no air. The lack of air allows the ice to absorb almost all visible light. This is why the ice appears so blue.
The ice caves are formed as the result of  
rain, snow and ice melting  on the glacier surface. Streams form and
 enter the glacier through the crevices.  The sediment in the 
surrounding soil causes the water to take on a muddy color while the top
 of the cave retains a blue tint. Some 
glaciers move quite rapidly, up to 1 meter per day. This causes the ice 
to 
crack  forming the cave. 
After donning helmets, our guide instructed us where to walk and where 
to stand, so as not to be in the path of any ice walls that may break 
off.  He pointed out one area in the cave where we could not stand, as 
he had heard it cracking just the day before!  Once I began 
photographing, I lost all fear of dying and was focused upon the task at hand .  
The 
resulting photo shown is a combined series of 5 images ranging in exposure from very dark to capture the detail of the sky, to very bright so that I could capture the detail of the interior of the cave. I then merged the 5 together to increase the range of tones.  This makes it possible 
to see all the detail inside the cave at the same time as the stormy sky
 that is outside the opening of the cave. 
