I was wandering through the woods one day when I stumbled into a large hole filled with salty water.  This was not uncommon, as I live near the ocean, but I was not expecting it and freaked out.  My thrashing led to a small opening appearing at the side of the pool growing larger until it revealed a large cavern.
The cavern was filled with a large pool of water and a rim running around the edge.  Down in the bottom of the pool there was some of the salt water that had been draining into the cavern which left it murky having a constant stream of bubbles and faint glimpses of red when the sun hit it at just the right angle.
I began coming back every night as it was a peaceful relaxing place and began to notice some of the salty water draining out of the bottom.  I began coming back because the stream of bubbles kept getting stronger as the water drained and I wanted to see what would be revealed.  About three weeks later I came back to watch the water finish draining and found a large, red, thing!  It looked like a fairy tale dragon with a glistening red hide and scales the size of turkey platters though it had no wings.
I gasped and the creature seemed to have heard me as it started digging.  At that moment the moon’s reflection hit me in my eye, blinding me.  When I could see again I looked into the pool but there was nothing of the creature left other than one of its turkey platter scales and a hole in the soft, wet, sand.