River Đáy
 The Day River (Vietnamese: Sông Đáy) is a river in Vietnam. It was formerly known as Sông Hát or Hát Giang. The river is a distributary of the Red River draining into the Gulf of Tonkin.The river has a length of 240 km and has a drainage basin of more than 7500 km² flowing through Hanoi and the provinces of Hòa Bình Hà Nam Ninh Bình and Nam Định.