Hong Kong UNESCO Global Geopark (香港聯合國教科文組織世界地質公園), formerly Hong Kong National Geopark (香港國家地質公園), was inaugurated on 3 November 2009. It is a single entity of land area over 150 km2 across parts of the eastern and northeastern New Territories. On 18 September 2011, UNESCO listed the geopark as part of its Global Geoparks Network.
The Hong Kong UNESCO Global Geopark consists of two geological regions:
- the Sai Kung Volcanic Rock Region, with its widely distributed tuff volcanic rocks displaying prismatic columnar jointing, which are of international geological significance
- the Northeast New Territories Sedimentary Rock Region, which comprises sedimentary rocks formed in different geologic periods, showcasing the complete geological history of Hong Kong.
High Island (糧船灣) is the home of the columnar-jointed volcanic tuff. Most of the columns are sub-vertical, straight-sided and parallel. It covers a large area around Sai Kung Peninsula in the eastern part of Hong Kong, including High Island Reservoir and Tai Long Wan.