Heron Island was discovered on 12 January 1843 by the corvette HMS Fly, the ship was surveying the eastern edge of the Great Barrier Reef. The expedition was commanded by Captain Francis Blackwood. The expedition intends to map out detailed plans for safe passages within the reef. On 11 September 1943 the entire island was declared a National Park. The Great Barrier Reef is the world’s largest reef system composed of over 2,900 individual reefs and 900 islands stretching for over 2,600 kilometers (1,600 mil) over an area of approximately 344,400 square kilometers (133,000 sq mi). The reef is located in the Coral Sea, off the coast of Queensland in north-east Australia.