Chongming Island is located at the mouth of the Yangtze River, with an area of 1000 square kilometers, ranking third after Taiwan Province Island and Hainan Island. It is also the only alluvial island among several large islands in China.

Chongming Island, shaped like a spring silkworm, is long from east to west and narrow from north to south. There are two islands beside Hengshan and Changxing. The formation of Chongming Island is related to the evolution of the Yangtze River estuary. Because the Yangtze River Estuary extends to the southeast, and Koumensha Island tends to tilt northward continuously, the position and shape of Chongming Island in the past are far from the present. According to research, about 1000 years ago in the Tang Dynasty, the Yangtze River estuary was in Yangzhou and Zhenjiang. At that time, Kumensha Island was just two small sandbanks in the river, called Dongsha and Xisha, with a small area of about tens of square kilometers. The ancestors of the island moved in from nearby Danyang and Jurong in Jiangsu Province to make a living by fishing. In the first year of Shenlong in the Tang Dynasty (705), Chongming Town was established in Xisha, which was probably the earliest appearance of the word "Chongming". Since then, Chongming Island has been going down the river, rising and falling. In the Song Dynasty, Yao quicksand was exposed in the northwest of Xisha, and three sands were accumulated in the northeast, while the original Dongsha and Xisha were gradually eroded by collapse. Next, the fate of Sansha, like Dongsha and Xisha, was gradually washed away, and the old one was replaced by the new one, under which sandbars such as Majiabang, Pingyangsha and Changsha were formed, among which Changsha was the predecessor of Chongming Island.

In the long river of history, many sand islands were tilted to the north or washed away in turn, but Chongming Island is at its peak today. Chongming Island is also unstable, even its county has moved again and again. In the 11th year of Wanli in Ming Dynasty (1583), Chongming County had moved five times. During the Guangxu period of Qing Dynasty (1875~ 1908), the south bank of Changsha silted up rapidly. Later, the local people built stone ponds and dams, which stopped the siltation and kept the county town stable.

At present, the trend of Chongming Island to the north is very obvious. The widest part of the north branch waterway is only about 1.5km, and the water depth is very shallow. The river bottom is silting up day by day. It is estimated that in the near future, Chongming Island will become a part of Qidong from an island with the siltation of the northern branch. Only in this way, today's Changxing and Hengsha Islands will replace Chongming Island.

Chongming Island is flat, with mountains and rivers like fields in the south of the Yangtze River. People who have just arrived in Chongming Island don't even feel that they are on the island. Patches of green crops, irrigation canals, dense villages and criss-crossing roads do not have the sense of desolation of an ordinary island.

But as an island, Chongming Island certainly has some unique resources and landscapes. Generally, there are three special sights: First, there are many crabs. On Chongming Island, especially on the mudflat near the sea, there are small crabs everywhere, and almost the whole beach is dark. Tourists walked on the beach, and crabs were frightened and fled into the powder-free holes on the beach. Amazing speed! It can be said that even if you bend down to pick them up at the fastest speed, it is difficult to touch them. Of course, it is not an exaggeration to describe the crab caves all over the beach with "riddled with holes". Therefore, Chongming Island is also called "Crab Island". Coupled with Chongming dialect, the word "what" is also pronounced as "crab", which sounds quite unique. Especially when local fishermen treat you with native crabs, you should politely say, "Nothing ("crab crab "), have some crabs!" It's interesting to sink at first, even if you look back later, you will feel where this experience can be found!

The second major feature of Chongming Island is the reeds on the beach, which is called "the Great Green Wall around the island". Because reeds are suitable for beach growth and grow very vigorously, we have seen reeds with a width of several kilometers on the north shore of Chongming Island and the Tuanjiesha area along the southeast coast. Walking in it, it seems endless, perhaps the scale of reeds in Shajiabang is just so. The original use of reed can not only protect the bank and promote siltation, but also be used as raw material for paper making.

The third feature is that the shape of the island is impermanent, and it is always in the process of rapid evolution. Chongming Island is different from bedrock island. In the past 100 years, it has basically maintained a relatively stable state, but it has been evolving from beginning to end. Blocking the North Branch and other projects are still in the pipeline. It seems that the day when China's third largest island evolved into land on the north bank of the estuary came earlier than expected.

Chongming Island also has a beautiful ancient name: "Yingzhou in the East China Sea". According to legend, in the ancient East China Sea, there was a place called Yingzhou, where immortals lived, but this fairy island has not been stabilized and has been erratic. Qin Shihuang and Han Wudi sent people to the East China Sea to look around, but they didn't find it. Later, Emperor Zhu Yuanzhang of the Ming Dynasty gave Chongming Island the word "Yingzhou in the East China Sea". Since then, Chongming Island has gained the reputation of ancient Yingzhou.