Tanintharyi or Taninthayi (widely known during the British occupation and since as Tenasserim) is a small town in Taninthayi Township, Myeik District, in the Tanintharyi Region of southwestern Burma (Myanmar). It is the administrative seat for the township. The town is located on the Great Tenasserim River which eventually enters the sea at Myeik. The town is located at the confluence of this river and a tributary known as the "Little Tenasserim River" which runs south.