In the early 20th century, when white settlers were venturing into Kenya, they came across a ‘kahenia’ (Kikuyu for shiny place) in Kiambu county that had an open lake. Legend has it that during the construction of the Kenya-Uganda railway by the Imperial British East African Company, the workers used to source water from the lake for construction and used the water as a coolant for the steam-powered engines of the trains. With time, increased human activity and natural occurrences turned this lake into a swamp: the Ondiri swamp.

Ondiri is a corruption of the English term ‘old lake’. Since 2016, Friends of Ondiri have made tremendous progress in restoring the lost glory of Ondiri. “This place looked like a tragedy of the commons,” Samuel Njoroge, who heads the ecotourism department, said. “People would dump waste right into the swamp. Sometimes we would camp at night, trying to identify these environmental polluters, but today it is no longer happening.”

The Ondiri wetland is a 40ha land close to Kikuyu town and along the southern Bypass. It is about 12-15m (39-50ft) deep, but some areas around the wetland are deeper. Ondiri is a unique wetland for it is the only one in Kenya exhibiting a highland quaking peat bog that is about 33.5ha and a forest cover that surrounds the region. It is the second-largest and deepest in Africa after the one in Douala, Cameroon. It changed from a lake to a swamp after it developed peat, a blanket-like structure formed by the accumulated deposit of decayed material that floats on top of a bog, which is the water beneath forming the wetland. Locals believe that if someone drowns in the swamp, the body is recovered in Lake Naivasha seven days later. Lack of rescue skills is said to have been the reason behind the myth. Walking on top of the bog gives a tickling bouncy feeling, as if you are walking on the surface of a bouncing castle. The wetland serves a community of more than 300,000 residents of Kikuyu. Households and even industries in the area directly or indirectly consume water from Ondiri. The swamp is also a source of water for the Nairobi river as it plays a part in the Athi Sabaki ecosystem. Water flows from the swamp into the Nairobi river, down to the Athi river, to Tana River and then empties to the Indian Ocean via the Sabaki river, which is on the Malindi-Sabaki estuary. Kikuyu Springs, a groundwater-protected zone in Magana Flowers, Kikuyu, recharges its water from Ondiri.