 The marine section of the park extends from an unnamed point north-east of Bishop and Clerk, westwards to Cape Boullanger and then southwards as far as Return Point.The marine boundary's definition varies, but it is never more than 1 km from Maria Island's low water mark.A ferry sails multiple times a day from the town of Triabunna to the jetty in Darlington Bay at the northern end of Maria Island, a distance by sea of 16 km or nearly nine nautical miles.