Porth yr Ogof
	The river Mellte disappears underground at this point in its course to re-emerge several hundred yards downstream at the blue pool. The north facing cave is shaded by the sides of a steep ravine, so two exposures were needed to blend together for this image to retain detail in the shaded areas and the water, while holding detail in the bright foreground.
	24mm  10sec and 3sec  f22 polarizer