Xinwanjin seawall is the longest seawall in the world, with a length of 33.9 kilometers. Once the longest seawall in the world was the afsluit seawall in the SUD sea of the Netherlands, with a length of 32.5 kilometers. The new Wanjin seawall is 1.4km longer than it. The original purpose of building the new Wanjin seawall is to obtain enough cultivated land to ensure food security in the future. The reclamation area of xinwanjin is about 140 times that of yoi Island, equivalent to about two-thirds of the area of Seoul.
The construction of xinwanjin seawall began in November 1991. Its initial purpose was to expand cultivated land and provide enough food through reclamation. This is a major event for South Korea, because it will change the territory of South Korea. Nearly 34 kilometers of seawall has replaced the world's longest seawall, the Netherlands xudehai afsluit seawall, which is 1.4 kilometers longer than it. It will be listed in the Guinness Book of world records.
Xinwanjin can be said to be the largest construction project in South Korea, using the most advanced and non-traditional construction methods in South Korea. The stone net method is adopted for the first time in the world. Large stones are placed in the net to overcome the very bad construction environment. The water velocity around the construction site can reach a maximum of 7 meters per second at rising and falling tides. The average water depth around the seawall is 34 meters, and the deepest depth can be 54 meters. The project turns the west coast of South Korea into a vast land and a lake with an area of 40100 hectares. South Korea has many plans for this land five times larger than Manhattan. The original plan was to allocate 70% of the land to farmers and the remaining 30% for industrial purposes. But now, due to the oversupply of rice, the original plan has been changed, 70% of which is used for industrial purposes or tourism, and the rest is used for agricultural production. Most of the land here will become tourist attractions.