Venezuela has the largest oil reserves, and the eighth largest natural gas reserves in the world. Compared to the preceding year another 40.4% in crude oil reserves were proven in 2010, allowing Venezuela to surpass Saudi Arabia as the country with the largest reserves of this type. The country's main petroleum deposits are located around and beneath Lake Maracaibo, the Gulf of Venezuela (both in Zulia), and in the Orinoco River basin (eastern Venezuela), where the country's largest reserve is located. Besides the largest conventional oil reserves and the second-largest natural gas reserves in the Western Hemisphere, Venezuela has non-conventional oil deposits (extra-heavy crude oil, bitumen and tar sands) approximately equal to the world's reserves of conventional oil. The electricity sector in Venezuela is one of the few to rely primarily on hydropower, and includes the Guri Dam, one of the largest in the world.