Located in the Hong Kong UNESCO Global Geopark in Port Shelter, Sai Kung, Sharp Island features some geo-trails and its clear waters make it a diving hot spot.  It consists of two small islands, Kiu Tsui and Kiu Tau, which look like separate islands at high tide while emerging as a tombolo at low tide.  Be sure to check the tidal predictions for when you can connect to the two islands on the underwater bridge, which will be quite an experience.  Since the island sits at the edge of a crater, there are a lot of geological wonders to explore, with many volcanic rocks, including quartz monzonite, whose cracks caused by weathering resembles the iconic local food pineapple bun. There are also attractive geosites introducing a variety of rocks such as volcanic breccia, weathered boulders, and volcanoclastic sedimentary rocks for visitors.