The Bug is one of the rivers whose name begins with the letter B. It is a tributary of the Narew River. The Bug flows through eastern Poland and western Ukraine and Belarus. The length of the river is estimated at 772 km. The area of the Bug basin is as much as 39,420 km2. It is the fourth longest river in Poland.
Biebrza is a river with the letter B, which is a right tributary of the Narew River. Its length is over 160 km. Biebrza is located in Poland, more precisely in its north-eastern part. The river connects with the Niemen via the Augustów Canal. The Biebrza basins are over 7,000 square kilometers.
Black Hańcza is a river with the letter B, which is a left tributary of the Niemen River. It is located in Poland and Belarus. The length of the river is 142 kilometers, and its basins are more than 1,900 square kilometers. It is the largest river flowing through the Suwałki region.
Black Dunajec is a river with the letter B. It is situated in southern Poland, in the Lesser Poland Voivodeship. The length of Czarny Dunajec is only 48 kilometers. It flows from the area of the Western Tatras and connects with Potok Jarząbczy, creating Potok Chochołowski, which in the lower parts is referred to as Siwa Woda. This process is the middle course of the Czarny Dunajec river. The lower course of the river begins when Siwa Woda joins Kirowa Woda.