Chinese National Geography Series for Kids

This book is a set of Chinese geography introduction tailored for children aged 10--14. It will provide children with a set of geographical thinking methods， using geographical thinking to measure and observe the land under their feet， and at the same time using the experience of walking on the route to experience our colourful China.

The Magnificent Blue Ocean Frontier and a Vast Resource Treasure

How big is China？ More than 9.6 million square kilometers？ That number only represents China’s land area. Seen from above， China lies in East Asia， on the eastern edge of the Eurasian continent and the western rim of the Pacific Ocean. Its maritime territory， like a blue torch， holds up the landmass. The Bohai Sea， Yellow Sea， East China Sea， and South China Sea together form approximately 3 million square kilometers of China’s blue domain， dotted with over 6，500 islands that are each over 500 square meters in size. These islands， along with the mainland’s coastline， create a shore that stretches for about 32，000 kilometers， recording a history of natural wonders shaped by the tides and the cycles of life.

The ebb and flow of the tides and the changing seasons make the ocean a giant influence on global climate， a vast repository of resources， and China’s gateway to the world. Together with the Land Silk Road， the Maritime Silk Road forms a link between China and other nations. The ocean， as the source of life， contains the planet’s most diverse ecosystems， as well as an abundance of water， salts， and marine biological and mineral resources， providing countless resources for human use. China benefits from the ocean’s bounty and is actively developing its marine economy as it moves toward becoming a strong maritime nation. Now， let’s dive in and explore China’s magnificent blue ocean frontier！

The Difference Between “Sea” and “Ocean”

In Chinese， “sea” and “ocean” are often described with a single term “海（hai），” but actually， “sea” and “ocean” aren’t quite the same. Geographically， both terms refer to large， interconnected bodies of saltwater on Earth， but they have distinct characteristics.

An ocean typically has an average depth of over 3，000 meters. Oceans are far from land （continents） and generally unaffected by the sediment inflow from rivers， which makes their water temperature and salinity relatively stable， and the water highly transparent. The vast， deep blue waters we often envision as “the sea” are actually more characteristic of oceans. The Earth’s oceans are divided by landmasses into four major interconnected oceans： the Pacific， Atlantic， Indian， and Arctic Oceans. In 2000， the International Hydrographic Organization recognized a fifth ocean， the Southern Ocean （also known as the Antarctic Ocean）. However， because this ocean lacks a distinct mid-ocean ridge （a continuous， submarine mountain range spanning the world’s oceans， of which the other four oceans each have one）， there is still academic debate surrounding its classification.

A sea， on the other hand， is situated along the edge of an ocean. Because seas are near land， they are more easily influenced by factors like rivers， groundwater， climate， and seasonal changes. This causes significant fluctuations in water temperature and salinity， and the water is less transparent. Seas can be categorized based on their location， such as marginal seas and inland seas. Marginal seas are located along the edges of continents and are separated from the ocean by peninsulas， islands， or archipelagos， and only connect to the ocean through narrow straits or channels. Examples include China’s South China Sea， the Sea of Japan， the Bering Sea， and the Sea of Okhotsk. Inland seas， such as the Bohai Sea in China， are situated further within continents and are enclosed by land or islands， only connecting to an ocean or another sea via a narrow strait.

In simple terms， oceans are broader and deeper， while seas are smaller， lying between ocean waters and land.

Is All Seawater Blue？

People often speak of the “blue ocean” and describe the sea as “deep blue，” making blue seem like the quintessential color of the ocean. But when viewed from above， China’s seas tell a different story. The Bohai Sea and Yellow Sea appear distinctly yellow， while the East China Sea transitions from yellow to greenish-yellow and then to a dark blue. Only the South China Sea fully displays the deep blue shade that aligns with most people’s expectations of the sea.

If you scoop a glass of seawater， you’ll notice that while it may appear a bit murky， it is generally colorless. So， why does the sea look blue from afar？ This phenomenon occurs because sunlight consists of various colors of light， each with a different wavelength. When sunlight strikes the ocean’s surface， longer wavelengths like red and orange are absorbed by the water， while shorter wavelengths like blue and violet are reflected. The human eye picks up this reflected light， giving the sea its blue appearance.

Beyond light， the color of seawater is also influenced by its depth and location. For example， the South China Sea has an average depth of over 1，200 meters and clear waters， which results in a deep blue hue.

The East China Sea， however， is a different story. Near river mouths， sediment-rich waters create a murky appearance， giving the sea a yellow or greenish tint. For instance， the Yangtze River deposits large amounts of sediment into the East China Sea， which is why the coastal waters here resemble the “Yellow Sea.” But as one moves southeastward （toward the open sea）， the East China Sea gradually shifts to a greenish-blue shade. In the southeastern corner of the East China Sea， warm， saline currents from the Kuroshio Current flow northward from the Pacific near the equator， cloaking the waters in a deep blue.

The Yellow Sea， by its very name， seems to be identified as a “yellow-colored sea，” but it is not entirely yellow. Before 1895， the Yellow River flowed directly into the Yellow Sea from what is now northern Jiangsu， carrying massive amounts of sediment. This made the Yellow Sea the world’s most sediment-rich marginal sea. The coast of northern Jiangsu near Yancheng has China’s largest mudflat and wetland， a typical example of a silt-laden coast， formed largely from sediment deposited by the Yellow River.

Bohai， an inland sea， receives vast amounts of sediment from approximately 40 rivers， including the Yellow River， into this semi-enclosed bay. Its nearshore waters are rich in sediment and thus appear a cloudy yellowish hue. Standing on the southernmost tip of the Liaodong Peninsula at Laotie Mountain， one can view the stark boundary between the Bohai and Yellow Seas： The turbid waters of the Bohai Sea sharply contrast with the clearer blue waters of the Yellow Sea. This boundary exists because the Yellow Sea in this area is less affected by sediment from nearby rivers， which keeps it clearer than the more sediment-rich Bohai Sea.

Zhoushan Archipelago

China’s Largest Archipelago

To the east of the vast， trumpet-shaped Hangzhou Bay， over a thousand islands stretch out in a northeast-southwest direction， forming groups such as the Shengsi Islands， the Qiqu Islands， the Zhongjieshan Islands， and five other island clusters， which together make up the Zhoushan Archipelago， China’s largest island group.

Records of the Zhoushan area date back to the Spring and Autumn Period， when it was broadly referred to as “Yong Dong，” meaning the east of the Yong River. The current name “Zhoushan” （meaning boat mountain in Chinese） first appeared during the Song Dynasty， with various explanations for its origin. Some believe it reflects the area’s strategic advantages for fishing， salt production， and maritime navigation， while others say it’s because the island resembles the shape of a boat. According to the Changguo Prefecture Gazetteer， compiled in 1298， the name “Zhoushan” comes from a small mountain on the island. This mountain， frequently used as a gathering and docking point for boats due to its unique location， led to the island being called Zhoushan， or “Boat Mountain.”

Zhoushan City is China’s first prefecture-level city based on an archipelago， consisting of 1，390 islands， about one-fifth of the nation’s total. Although scattered across the vast sea， these islands are inseparable from Zhejiang’s Tiantai Mountain Range in the province’s east-central region. Around ten thousand years ago， rising sea levels submerged low-lying lands， transforming the area into its current form. Thus， the Zhoushan Archipelago is a typical continental island group.

One of the Busiest Ports

With established transportation， the Zhoushan Archipelago is strategically positioned to leverage its geographic advantage and excellent port resources， contributing significantly to China’s marine economy.

Situated along China’s eastern golden coastline， it borders the expansive economic hinterland of the Yangtze River Delta （including Shanghai， Hangzhou， and Ningbo） and extends outward into the western Pacific. As the intersection of China’s coastal routes and the Yangtze River， Zhoushan serves as a key maritime gateway and access point for the Yangtze Basin and the Yangtze River Delta’s international trade. The archipelago’s coastlines are primarily rocky， with deep waters near the shore and numerous channels， providing ideal port conditions. Studies show that Zhoushan’s deepwater coast suitable for port development extends for more than 280 kilometers， making it the only area in the Yangtze Delta with continuous deepwater coastlines. If fully developed， Zhoushan’s port capacity could exceed a billion tons annually. Established in 1985， the core port area of Zhoushan Port has a main channel depth exceeding 22.5 meters， allowing 300，000-ton vessels to pass freely， and even 400，000-ton supertankers can enter with tidal assistance. Currently， Zhoushan Port connects with over 600 ports across more than 100 countries and regions， making it one of the busiest ports worldwide.