Tourism has become one of the main drivers of the economy, with tourism estimated at $1.8 billion to the economy in 2008. Guatemala receives around two million tourists annually. In recent years, there has been an increase in the number of cruise ships visiting Guatemalan seaports, leading to higher tourist numbers. Tourist destinations include Mayan archaeological sites (e.g. Tikal in the Peten, Quiriguá in Izabal, Iximche in Tecpan Chimaltenango and Guatemala City), natural attractions (e.g. Lake Atitlán and Semuc Champey) and historical sites such as the colonial city of Antigua Guatemala, which is recognized as a UNESCO Cultural Heritage site.