The Zwaardvis class submarine (Dutch: "Swordfish") is a conventional attack submarine that replaced the Dolfijn class in the Royal Netherlands Navy. Zwaardvis is based on the U.S. Navy Barbel class with the teardrop hull design. In September 1981 the Republic of China (Taiwan) ordered two modified Zwaardvis class submarines, the Chien Lung/Hai Lung class. In 1992 a repeat order for another 4 boats was turned down by the Netherlands Government because of pressure from the People's Republic of China. The two Dutch boats have been replaced by the Walrus class.