In this expedition, Sarawak chamber, which lies in the Gua Nasib Bagus was discovered.[3] In 1984, Gunung Mulu was designated as ASEAN Heritage Park.[7] In 1985, the park was officially opened to public.[3] In a British expedition in 1988, a link was established between Clearwater Cave and Cave of the Winds which extends the Clearwater cave to 58 km (190,000 ft), claimed to be the longest cave passage in Southeast Asia. Blackrock Cave was also discovered during this expedition.[8] In 1991, a connecting passage was discovered between Blackrock Cave and Clearwater Cave. This extends the Clearwater Cave passage to 102 km (335,000 ft), leading it to be the 7th longest cave passage in the world.[3] Between 1993 and 2000, British expedition teams explored the eastern flank of Mount Api with several discoveries made in the Hidden Valley.[3]