Question: What city situated at the northern extremity of Brisbane Water, is also where the Central Coast Mariners FC is based?
Sentence (from "Brisbane Water"): A number of towns surround the shores of Brisbane Water, including Booker Bay, Davistown, Ettalong Beach, Gosford, Green Point, Kincumber, Phegans Bay, Saratoga, Wagstaffe, and Woy Woy.
Relevant evidence: No