This peaceful spot of water is located at Pedernales Falls State Park, just west of Austin. We were hiking all around the park, generally just enjoying the natural beauty and the sounds of the multiple waterfalls. It's a great spot, and the day we were there the weather was clear and beautiful too. It looks like a wonderful place to take a dip, though if I recall correctly you are not allowed to swim here due to fast-moving currents. The other thing is that this water is really deep! Even with HDR, the photo doesn't entirely do it justice. If I had to guess, I would say it was 10+ feet deep here, and there were other pools we walked around that I bet went as deep as 20 feet. The clarity of the water is excellent, as you can plainly see, so that makes it harder to judge but pretty to look at!
This is a 7 exposure HDR taken at f/22, with exposures ranging from -4 to +2. They were merged in Photomatix to create the HDR image, then adjustments and some minor corrections were made in PSE and Aperture, such as adjusting contrast. I then added a light touch in Topaz Adjust.