Hinchinbrook Island (or Pouandai to the Biyaygiri people) is an island in the Cassowary Coast Region, Queensland, Australia. It lies east of Cardwell and north of Lucinda, separated from the north-eastern coast of Queensland by the narrow Hinchinbrook Channel. Hinchinbrook Island is part of the Great Barrier Reef Marine Park and wholly protected within the Hinchinbrook Island National Park, except for a small and abandoned resort. It is the largest island on the Great Barrier Reef. It is also the largest island national park in Australia. Natural heritage Hinchinbrook Island is made up of late Palaeozoic igneous rocks. The main pluton in the east of the island, the Hinchinbrook Granite, is composed of various hypersolvus granites and intrudes volcanics, granodiorites, and granites. The island and coastal ranges are thought to have been thrust up as blocks with subsidence between them to form the coastal plain with the summit level of the island being an older dissected surface that has been uplifted to approximately or more above sea level. The Hinchinbrook Channel that separates the island from the mainland is considered to be fault controlled. Since the last Ice Age 18,000 years ago sea level has risen. Once there was a significant rugged coastal range, now there is Hinchinbrook Island. To the west is the mangrove-fringed Hinchinbrook Channel with of robust mangrove estuaries. The channel is the valley of the Herbert River flooded following the last glacial period. The island is only separated from the mainland at times of high sea-level such as the present and is thought to have had dry land connections to the mainland for most of the past few million years. Further west is the Cardwell Range Escarpment rainforest. East of Hinchinbrook Island lies the Coral Sea, Great Barrier Reef Lagoon and Great Barrier Reef. To the north of Hinchinbrook Island, Rockingham Bay hosts densely vegetated continental islands, e.g., Garden Island, Goold Island, Brook Islands Group, Family Island Group, Bedarra Island and Dunk Island east of Mission Beach. South of Hinchinbrook Island, the Cardwell Range gives way to the Herbert River floodplain and delta. Missionary Bay is at the northern end of Hinchinbrook Island National Park. Natural features of this biodiverse area include of dense mangrove communities lining the shoreline. Many botanists believe the mangrove forests along the island's western coast are the most diverse in the country. 31 different species of mangrove has been identified. A