The Sea Quest was a semi-submersible platform that discovered the UK's first North Sea oil on 14 September 1970 in the Forties oilfield. The Sea Quest was built by Belfast shipbuilders Harland and Wolff for British Petroleum at a cost of £3.5 million and launched on 8 January 1966. The entire structure was 320 feet high and weighed 150,000 tons, including three legs, each of which was 35 feet in diameter and 160 feet long. Each leg could be partially filled with water to control the height of the platform above the sea.