Thua Thien-Hue Province plain along the sea coast has many lagoons, such as those of Tam Giang, Thuy Tu, Lap An, into them are converged the water of almost all the rivers of the province of Thua Thien Hue before going to the sea, through the mouths of Thuan An, Tu Hien, or through the great lagoon of Lang Co. Tam Giang and Cau Hai are the 2 biggest lagoons with fresh water, the 2 most representative lagoons in Vietnam with a length of 70km for the whole of the two, they form an ideal habitant for many sea species all along the province.

Yearly thousands tons of sea products are brought on here (fish, shrimps and others). In the recent years, the cultivation and raising of sea products, mainly the raising of shrimps and cultivation of "gracilaria" has developed in this zone of lagoons.