In May 1963, Norway asserted sovereign rights over natural resources in its sector of the North Sea. Exploration started on July 19, 1966, when Ocean Traveller drilled its first hole. Initial exploration was fruitless, until Ocean Viking found oil on August 21, 1969. By the end of 1969, it was clear that there were large oil and gas reserves in the North Sea. The first oil field was Ekofisk, which produced 427,442 barrels of crude in 1980. Subsequently, large natural gas reserves have also been discovered and it was specifically this huge amount of oil found in the North Sea that made Norway’s separate path outside the EU possible.