Agriculture was once the chief economic activity in Guyana, despite the coastal plain which comprised only about 5 percent of the country's land area being suitable for cultivation of crops. Much of this fertile area lay more than one meter below the high-tide level of the sea and had to be protected by a system of dikes and dams, making agricultural expansion expensive and difficult. In the 1980s, there were reports that the 200-year-old system of dikes in Guyana was in a serious state of disrepair. Guyana's remaining land area is divided into a white sand belt, which is forested, and interior highlands consisting of mountains, plateaus, and savanna. 2% of the land is arable land.