Someswari is the largest and the second longest river in the
West Garo Hills District. Locally known as Simsang, the river starts from Nokrek peak and runs towards east, passing through Rongrengiri, Williamnagar the headquarters of
East Garo Hills District, Nongalbibra,
Siju, Rewak and finally
Baghmara the headquarters of
South Garo Hills District. The lower course of the river has many deep pools and falls. The chief tributaries are Chibok, Rongdik, Rompa and Ringdi rivers.
