In Dong Hoi City (Quang Binh Province). Previously an arm of the sea, now partly filled in by shifting dunes which have thus created a freshwater lake (according to Le Quy Don in his Phu bien tap luc).

Bàu Tró at Dong Hoi, Quang Binh

Bàu Tró at Dong Hoi, Quang Binh

There are many other lakes formed the same way in this province.