Which sea area does Zhoushan Islands belong to?

1, Zhoushan Islands belong to the East China Sea.

2. Zhoushan Archipelago is the residual vein of Tiantai Mountain range in eastern Zhejiang, extending to the sea. From 1000 to 8000 years ago, the mountains were submerged because of rising sea level, forming today's islands. The highest peak of the archipelago is the confrontation mountain of Taohua Island, with an altitude of 544.4 meters. The whole archipelago belongs to the landform type of low mountains and hills. With the rise and fall of sea level and long-term wave erosion, marine terraces and caves have developed on the island. 10-meter-high sea erosion terraces can be seen everywhere on Zhoushan Island, and 30-meter-high terraces are more clear. Tidal caves in Putuo Island belong to sea caves. Tide, like a big porter, carries a lot of sediment to the hidden area of the island for deposition, connecting several islands and forming the accumulation plain on the island. Zhoushan Island, Zhujiajian Island Island and Daishan Island are all big islands formed by the expansion of marine plains. Geographically, Zhoushan Archipelago belongs to a part of Cathaysian mainland, and its stratum is the same as that of eastern Zhejiang. Most of them are composed of Mesozoic volcanic rocks, gneiss, marble and other ancient metamorphic rocks and Cenozoic basalt. Since Quaternary, with the rise and fall of sea level, marine gravel layers and muddy beaches have been deposited.