This panorama shows Planinska jama (The Planina cave) which is one of the longest Slovenian water caves.
I was able to visit this cave at the annual PanoTools-Meeting 2015.
As the lens is a fisheye lens, four pictures easily cover 360°. To capture the large dynamic range of the scenery I took three exposures in each direction. I used a custom lens bracket on a tripod. The exposures were 2 f-stops apart. The exposures were blended in Lightroom and exported to be stitched with PTGui Pro. Zenith and nadir were retouched by hand in Photoshop.