The World is a man-made archipelago of 300 islands in the shape of a world map. The World is being built primarily using sand dredged from the sea. Each island ranges from 23,000 m2 to 84,000 m2 (250,000–900,000 square feet or 5.7–21 acres) in size, with 50–100 m of water between each island. The development will cover an area of 9 km in length and 6 km in width, surrounded by an oval breakwater. The only means of transport between the islands will be by boat and helicopter. Prices for the islands will range from $15-45 million (USD). The average price for an island will be around $25 million (USD). Dredging started in 2004 and as of March of 2007 The World is around 90% complete. According to the National Geographic Channel (The Best of Megastructures) the overall price for the World is $14 Billion US Dollars.