Currently, in the world as well as in Vietnam, the activities of dumping materials in the sea, especially in the seaports and creeks that is taking regularly. According to statistics from the Ministry of Natural Resources and Environment (MONRE) a total of 25 dumping licenses have been granted nationwide until 2021 for the disposal of dredged materials in the sea. Of these, 6 were issued by local governments and 19 were issued by MONRE. The volume of dredged materials dumped under these licenses is nearly 74 million m3. Circular No. 28/2019/TT-BTNMT, dated December 31, 2019, on technical regulation on evaluation of dredged material and determination of dumping dredged materials area in Vietnamese seas, specifies the identification of the marine areas used for dumping dredged materials. However, one of the crucial elements in establishing the dumping area is the required depth for dumping, which is not specified in this rule in a precise or quantitative manner. In order to propose the proper depth for dumping dredged materials in Vietnamese waters, this paper will concentrate on study in that area.