Hong Kong Volcanic Wonderland High Island Reservoir East Dam is situated within Hong Kong UNESCO Global Geopark, is home to breathtaking rock landscapes of international geological importance formed when a supervolcano erupted 140 million years ago. It offers Instagram-worthy views of the reservoir, dam and breakwater dolosse, or double T-shaped concrete wave breakers including towering cliff faces lined with hexagonal rock columns, including towering cliff faces lined with hexagonal rock columns, mysterious caves and sea stacks and coastal scenery.