Ngo Tran Hai An, a travel blogger and photographer, has visited over 100 land and island border markers in Vietnam and around the world for 19 years.
When An visited Con Dao Archipelago in southern Vietnam with his family, he decided to track the A3, A4, and A5 landmarks. These are three of the 11 baseline location points, marking Vietnam's territorial waters, which are located along its 3,260-kilometer coastline. Most of the points are on remote islands and difficult to reach.
An said in 2010, he started off visiting 11 landmarks in 11 years, Con Dao marking 9 out of 11.