River systems of Thailand divides into two major branches, the " Tiền Giang" (Front River) and "Hậu Giang" (Back River). These in turn enter the South China Sea through nine estuaries. The following are the principal tributaries of Mekong River which flow through Thailand (tributaries entirely outside the Thai border not shown). The Mekong drains a considerable portion of northeast Thailand. In terms of Thai territory drained, it is second only to the Chao Phraya system. The Salawin River rises in Tibet (Tibetan: རྒྱལ་མོ་རྔུལ་ཆུ།) after which it flows through Yunnan, where it is known as the "Nujiang" River (), although either name can be
Suárez River horse drowned in the river when it experienced sudden flooding. The original name in Chibcha, given by the Guane was "Saravita", meaning "departs from here". The Suárez River is long and its drainage basin extends over , of which in Santander. It is sourced by Lake Fúquene in Boyacá at an altitude of and forms together with the Chicamocha River the Sogamoso River in Santander at an altitude of . The river starts on the Altiplano Cundiboyacense where it forms the boundary between Cundinamarca and Boyacá and for a major part of its course downstream it is the natural boundary