The site comprises a system of seven watercourses within the
Christmas Island National Park, including permanent and perennial
streams, permanent
springs, the Hugh's Dale waterfall, and most of the surface water on the island. It was designated on 21 October 2002 as Ramsar Site 1225, and is the first Australian Ramsar site to contain both surface and subterranean
karst features. Area of Ramsar site is about 57 ha. It was also listed on the
Directory of Important Wetlands in Australia prior to 2001. Interesting geological features of the Dales are
travertine and
rimstone formations of Hugh's Dale and the gully of Sydney's Dale, which closer at the sea gets up to 12 m deep and 9 m wide. ==Flora and fauna==