Yanhai Well, near a weir called Changyantang, covers an area of 0.2 hectare and it is 341.4 meters high. It was dug in 1832 and accomplished three years later. The Well is 1001.42 meters deep, the main buildings around it are: awl room, carport, kitchen and cashier office, ect. It has a great deal of facilities, such as awl stand, derrick, boiler and storehouse. The Well produced bittern and gas, and according to the recordation, it is the major gas producer at the time. After the maintenance in 1984, Yanhai Well displays the prosperous vision of soil producing in the old times and a complete set of traditional crafts to dig well, produce and transport gas, decoct soil, ect.