The ancient sea pond was built in the fourth year of Emperor Zhaozong of the Tang Dynasty (897 AD). It was a tutang at that time, and it was converted into a stone pond during the Jiading period by Chunxi of the Southern Song Dynasty. Starting from Jinzi Mountain in the east, extending to Dongguan Township one after another, it is 4800 meters long, 14 meters wide and 5 meters high. It is all built of slabs and slabs. The structure is unique and the craftsmanship is exquisite. It is also known as the "Little Great Wall in East Zhejiang" , Known as "the integration of the city and the pond, the first in the world".