Saiwa is the smallest park in Kenya, only 3 km2. It is situated below the Cherangani Hills, Trans-Nzoia District of Rift Valley Province. It was established to protect the semi-aquatic antelope, Sitatunga and encloses the swamp fed by the Saiwa river together with its fringing belts of rain forest. The park is enclosed by subsistence farming settlements.
Vegetation is a mixture of forest and swamp vegetation. The swamp is dominated by tall bullrushes and sedges. The swamp is bordered by a mixture of grassland, riverine forests and Acacia.