Central Rila Reserve is a nature reserve in Rila National Park, located in the Rila mountain range in southwestern Bulgaria. Spanning a territory of 12417 ha or 124.17 km2, it is the largest nature reserve in the nation and the Balkan Peninsula. It was declared in February 1992 to protect undisturbed primary alpine ecosystems. Upon its creation, the Central Rila Reserve included the whole territory of the previously existing since 1956 Marichini Lakes Reserve, and the latter seized to exist as a separate protected area, which had been part of the UNESCO Biosphere Reserve since 1977. It is a strict nature reserve.