Fraser Island, island off the southeastern coast of Queensland, Australia, separated from the mainland by the Great Sandy Strait and Hervey Bay, facing the town of Maryborough. Fraser Island is the world's largest sand island. It is about 110 km (about 70 mi) long and ranges in width from about 7 to 23 km (about 4.5 to 14 mi). The island's sandhills, which are up to 400,000 years old, rise to heights of about 240 m (about 790 ft). Rain forests grow on the sand dunes of Fraser Island, unlike on other sand islands. Hoop, kauri, blackbutt, and satinay trees are common. There are more than 40 deep freshwater lakes on the island, some of which are perched high above sea level. Lake Boemingen, the largest of these lakes, is almost 200 hectares (almost 500 acres) in area. Prior to European occupation the island was home to several thousand Aboriginal Australians. The island is exceptionally rich in plant life. There are well-preserved tidal marshes, subtropical rain forests and communities of mangroves on the western side of the island, and heaths and open forests on the east. Humpback whales are sometimes seen offshore. Much of the island is protected as the Great Sandy National Park. In 1992 the park was inscribed on the World Heritage List, a listing by the World Heritage Convention of the world's unique and precious places.