From its source to its outlet into the Black Sea , its main tributaries are ( in order that they enter ) :
Many Danubian tributaries are important rivers in their own right , navigable by barges and other shallow - draught boats .
From its source to its outlet into the Black Sea , its main tributaries are ( in order that tributaries enter ) :
Many Danubian tributaries are important rivers in their own right , navigable by barges and other shallow - draught boats .