Оңтүстік Африканың Гамтоос өзені

River in the Eastern Cape, South Africa

Gamtoos River or Gamptoos River is a river in the Eastern Cape Province, South Africa. It is formed by the confluence of the Kouga River and the Groot River and is approximately long
with a catchment area of .

The Gamtoos river system is formed by the Groot, the Kouga and the Baviaanskloof rivers. The latter is a tributary of the Kouga. Although the rainfall in the catchment area is low, it supports a commercial irrigated agriculture in the lower catchment in which oranges, tobacco, citrus fruit and vegetables are grown. There is an estuary where the Gamtoos river enters the Indian Ocean. It is located between Jeffreys Bay and Port Elizabeth and the Gamtoos River Mouth Nature Reserve is in the area. The towns of Hankey, the oldest town situated in the Gamtoos river valley, and Patensie are situated in the lower catchment. Further inland are the towns of Steytlerville, Joubertina, Uniondale, Willowmore and Murraysburg. Tributaries include the Loerie River, Klein River, Hol River, besides the Groot and the Kouga that form the Gamtoos.

Saartjie Baartman the "Hottentot Venus" was born around 1789 in the vicinity of the Gamtoos river. In 1877 during a severe drought in the region, the Gamtoos River dried up completely. During the floods of October 1867, according to John Croumbie Brown, the level of water in some parts of the river rose by up to 70 feet (21 m). Two bridges cross the Gamtoos close to its mouth in the Kouga. The original 600 feet (183 m) bridge on the R102 was opened in 1895 in order to replace the ferry that had been in use up to that time. A modern concrete bridge was built during the construction of the N2 in the early 1970s.

In 1995 specimens of the Cape galaxias (Galaxias zebratus), a South African fish species endemic to the Cape Floristic Region, were found in the Krom River and subsequently they were also found in the Gamtoos River system. Until then it had been thought that its distribution was restricted to the area between the Keurbooms and the Olifants River. Although in South Africa this relatively delicate fish is only classified as near threatened, in Australia species of the same genus were driven to extinction by competing salmonids and other introduced species of fish.