High Quality Content by WIKIPEDIA articles! The Mary River is a river system in South East Queensland, Australia. The river rises at Booroobin in the Sunshine Coast hinterland, west of Landsborough. From its source, the Mary River flows north through the towns of Kenilworth, Gympie, Tiaro and Maryborough before emptying into the Great Sandy Strait, a passage of water between the mainland and Fraser Island, near the town of River Heads, 17 km south of Hervey Bay.