Perhaps in a legend with numerical indicators at the proper coordinates? A pop-up box when a cursor covers said numerical designator should work if you're referencing electronic maps.
you read or hear guys talking about fishing inside turns and bottlenecks, what do you look for on lets say Navionics to identify and inside turn or a bottle neck. Would this be considered a bottleneck in the picture, where its just a long narrow flat stretch?
Bottleneck. Its kind a like a bridge. There are many roads to lead up to it. But only a narrow little path to get thru. Then once on the other side it spreads back out again.