This is the fresh water spring of the island/of the land anywhere close to Siracusa.  It was for this reason people were able to settle in Siracusa.  There is a lovely myth about two lovers that deals with this water spring but . . . the sea was occupying my mind at the moment.  Anyways, there are fish living in there, and, interestingly, it is literally right next to the bay area – wonder if it gets contaminated by the salt water.  (taken 28.2.2015)