Brighton Beach had a marvelous sandy coast looking out on the Atlantic and the adjacent Coney Island amusement park, all just ten miles from Manhattan -- everything one could ask for in a delightful seaside resort.
I'm not quite sure how to understand 'all' in the context. Does it mean the distance between Coney island and Manhattan totally just ten miles? Or it refers to all the areas that have been mentioned in the first part of the sentence including Brighton Beach, Coney Island, and etc.?
What's the correct way to understand it?