I went diving with my friends Jack and Jane yesterday. When we left the dock, the fog was starting to burn off, but there was still a high overcast. Jack chose to anchor between Lanes Cove and Folly Cove, predicting correctly that we would be sheltered on the northern side of Cape Ann. The water was a smooth as glass.
Perhaps a better simile would be as smooth as a bowl of soup. Whether it was the overcast above, or simply an abundance of plankton below, the visibility was pretty crummy, at only about five feet or so.