Buried below the Boreal Forest of northern Alberta is 3rd largest proven reserve of oil known as the tar sands. Deposits of tar sands are spread out over 138 000 km2 of land (an area the size of Florida) and including 4.3 million hectares of the Boreal Forest. Tar sands are solid at room temperature so it requires more energy and water to extract this oil, making them one of the dirtiest oils on the planet.