With 102km of coastline and 17,000km2 of territorial waters, Thanh Hoa has long been a bright spot of domestic tourism. However, in recent years, people in coastal communes of Thanh Hoa province have always had to endure the scene of beaches piled up with plastic waste, potentially spreading the disease. This amount of plastic waste tends to increase with the development of economic activities, production, and tourism in the province.

Hai Phong sea area has an area of about 4,000 km2, 2.6 times more than the city's land area, accounting for 5.4% of the Gulf of Tonkin area. Hai Phong is located on the northwest coast of the Gulf of Tonkin with a coastline of about 125 km, with 6 main estuaries flowing into the sea. With 8/15 districts adjacent to the sea and 2 island districts of Cat Hai and Bach Long Vi, the city's marine tourism resources are mainly concentrated in Cat Ba, Do Son, and partly in Bach Long Vi. Hai Phong has more than 400 islands, concentrated in the Cat Ba archipelago (367 islands) with an area of 334.1 km2, of which Cat Ba limestone island is one of the three largest islands in our country and the only large limestone island.

With 72 km of coastline, Nam Dinh province creates favorable conditions for exploitation, aquaculture, seafood, and tourism service development. Thinh Long tourist area, Hai Hau district and Quat Lam tourist area, Giao Thuy district are the tourist attractions of the province. In addition, Nam Dinh province has 4 large rivers flowing into the sea: Red River, So River, Ninh Co River and Day River.