In your photograph (perhaps not in real life, I don't know) it looks frightening. As if the hole might draw you in. I once came across an isolated highland tarn in Scotland that had the same effect upon me. Perfectly circular, full to the brim and its water black as night.
Hi ,i know the effect you mean ,here there were a lot of volcanic holes,some big some small and it was so scary to stretch and look down , the very thought of falling in was beyond believe as it was just the sea at the bottom , this photo is as it was (its not been edited )