An expansive energy frontier bordered to the north by the largely untapped and isolated Arctic environment, Russia contains the world's largest natural gas reserves, estimated in 2008 at 1,680 Tcf, as well as the world's eighth largest oil reserves of some 60 billion barrels, predominantly in Western Siberia. Situated in the harsh waters of the Barents Sea and one of the largest gas deposits ever discovered, the Shtokman gas and condensate field holds an estimated 19 billion barrels of oil equivalent and is operated by Russian energy giant Gazprom. As the world's most prolific natural gas extractor, Gazprom is a primary purveyor of gas supplies to many euro zone countries.