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
River Lea Fish Island), Poplar, Canning Town and finally Leamouth where it meets the River Thames (as Bow Creek). It forms the traditional boundary between the counties of Middlesex and Essex, and was used for part of the Danelaw boundary. It also forms part of the boundary between Essex and Hertfordshire. For much of its distance the river runs within or as a boundary to the Lee Valley Park. Between Tottenham and Hackney the Lea feeds Tottenham Marshes, Walthamstow Marshes and Hackney Marshes (the latter now drained). In their early days, Tottenham Hotspur and Leyton Orient played their matches as football amateurs