About Tasmania. Tasmania is the island State of Australia. It lies 240 kilometres south of the Australian mainland. Located between 40 degrees S and 43.30 degrees S, it is surrounded by the Southern Ocean (to the south and west), the Tasman Sea (to the east) and Bass Strait (to the north).t lies 240 kilometres south of the Australian mainland. Located between 40 degrees S and 43.30 degrees S, it is surrounded by the Southern Ocean (to the south and west), the Tasman Sea (to the east) and Bass Strait (to the north).