There are only two wine growing regions in Bulgaria: the Thracian Lowlands and the Danubian Plain. The latter lies south of the iconic Danube River, with the Black Sea to the East and Serbia and Macedonia to the West. The region enjoys as many sunlight hours during the growing season as Northern Italy and Portugal, allowing for full ripening of both international and indigenous varieties. The movement of the Danube River, as well as the influence of the Black Sea, moderate heat during the day and keep the evenings cool, ensuring brilliant acid levels in the wines. The yields are remarkably small in Bulgaria, with an average of only 4.3 tons/ha. By comparison, the US averages 18 tons/ha. Jancis Robinson has noted the exceptional potential of this northwestern part of Bulgaria and the wine world is starting to pay attention.