Flói, the agricultural area between the rivers Ölfusá–Hvítá and Þjórsá, reaching inland to the Merkurhraun lavafield. Flat country with the occasional hill, the Þjórsárhraun lava field being the “bedrock” under the soil. In 1927 a remarkable irrigation project was undertaken, using the river Hvítá and constructing the Flóaáveita system of 300 km of ditches and 450 km of dykes to irrigate an area of 12 thousand hectares.