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
Malaysia–Thailand border sea boundary in the Gulf of Thailand while a separate memorandum of understanding signed in 1979 established a short continental shelf boundary in the area. The boundary beyond that agreed is subject to dispute because of overlapping claims over the seabed. The overlapping claims led to the establishment of a joint development area in 1990 where both countries agreed to share mineral resources in a 7,250 square km wedge-shaped area. From west to east, the 646.5 km Malaysia-Thailand border begins at a point which lies just north of the Perlis River estuary as defined in the schedule of the Anglo-Siamese