The left tributary of the river Bug is 120 km long. It flows through
Southern Podlasie and Southpodlasian Plains. It emerges from the combination of
two streams flowing through the forests on Łukowska Plain: Northern Krzna and
Southern Krzna. These rivers merge in Międzyrzec Podlaski. The Krzna flows into
the Bug near the village of Neple.
