Mzima Springs are a series of four natural springs in Tsavo National Park, Kenya. They are located in the west of the Park, around 48 km from Mtito Andei. The source of the springs is a natural reservoir under the Chyulu Hills to the north. The Chyulu range is composed of volcanic lava rock and ash, which is too porous to allow rivers to flow. Instead, rain water percolates through the rock, and may spend 25 years underground before emerging 50 kilometres away at Mzima. The natural filtration process gives rise to Mzima's famously clear stream, which flows through a series of pools and rapids. Two kilometres downstream from the springs, the stream is blocked by a solidified lava flow and disappears below the surface again. Mzima is one of Tsavo's most popular wildlife attractions owing to its resident populations of hippos and Nile crocodiles. Mzima's isolation makes both species are dependent on its waters: other sources are too distant for them to reach by overland travel. The hippos also sustain an entire food chain. They browse the surrounding savannah by night and return to Mzima's pools by day, where their dung fertilizes the water. The biggest attraction in Tsavo West is Mzima Springs, this stream of crystal-clear water was made famous by Alan Root’s 1983 film Mzima: Portrait of a spring, which followed crocodiles and hippos in their underwater lives. It’s a delightful, and popular, spot, so you’re advised to arrive very early to avoid a possible tour-bus atmosphere.