The Gulf of Carpentaria is the largest semi-enclosed body of water in Australia. It lies within the tropical Indo-West Pacific region, a vast biogeographical zone stretching from the east coast of Africa to the islands and atolls of the western Pacific ocean. With research largely related to prawn fisheries and concentrating on the area deeper than 20 m there is a zone of coastal water up to 20 km wide along much of the Gulf coast which has received little scientific attention. Lying entirely within the tropics, the climate is characterised by constantly high temperatures, 12 hours of daylight almost year round and a heavy, markedly seasonal annual rainfall under the influence of the monsoon. Rainfall decreases with increasing latitude and the pattern of alternating flood and drought is a dominant feature of the climate. High levels of cyclonic activity are both destructive (loss of seagrass and mangroves) and constructive with run-off from heavy rains mobilising large quantities of sediment into southern Gulf coastal habitats and recharging aquifers. One of the four major drainage systems in northern Australia, the Gulf is a shallow, large embayment formed when the brackish Lake Carpentaria was flooded between 10 000 and 6 000 years ago.