Dnieper-Boh Estuary or Dnieper Estuary. (Map: Dnieper-Boh Estuary.) Bay created by the flooding of the mouths of the Dnieper River and Boh River by the Black Sea, from which it is separated by the Kinburn Spit. It is 55 km long, 4–12 km wide, and 1–2.3 m deep. The water is brackish; the estuary freezes for two months.