This is a list of rivers in Bulgaria, organised geographically, taken clockwise from the westernmost tributaries of the Danube drainage. Tributaries are listed down the page in an downstream direction, i.e. the first tributary listed is closest to the source, and tributaries of tributaries are treated similarly. The main stem (or principal) river of a catchment is labelled as (MS), right-bank tributaries are indicated by (R), left-bank tributaries by (L). Note that in general usage, the 'right or left bank of a river' refers to the right or left hand bank, as seen when looking downstream. The list encompasses most of the main rivers of Bulgaria. It includes rivers shared with other countries. There is also a list of rivers over 50 km. The Bulgarian word for river, река (transliteration reka) is often a part of the river names in the country.