Kenya occupies 580,367 square kilometers in East Africa, straddling the equator between latitudes 4°40'N and 4°40'S. The country shares borders with Somalia (682 kilometers) to the northeast, Ethiopia (867 kilometers) to the north, South Sudan (317 kilometers) to the northwest, Uganda (814 kilometers) to the west, and Tanzania (775 kilometers) to the south. The Indian Ocean coastline extends 536 kilometers along the eastern boundary. This positioning places Kenya at the intersection of three major African biogeographic zones: the Somali-Maasai savanna ecosystem, the Guineo-Congolian rainforest belt extending from West Africa, and the Afro-alpine highlands found only in isolated East African mountain ranges.
The Great Rift Valley divides Kenya along a north-south axis, entering from Ethiopia near Lake Turkana and continuing southward through Lake Baringo, Lake Bogoria, Lake Nakuru, Lake Naivasha, and Lake Magadi before crossing into Tanzania. This geological trench formed approximately 20 million years ago as tectonic forces began pulling the African and Somali plates apart. The valley floor ranges from 450 meters above sea level at Lake Turkana to approximately 1,890 meters at Lake Naivasha. Escarpments rise 600 to 900 meters above the valley floor on both sides, creating dramatic topographic variation within short horizontal distances. The Rift Valley system contains over 30 lakes in Kenya, most of them alkaline due to volcanic mineral deposits and high evaporation rates in the enclosed drainage basins.
Mount Kenya rises to 5,199 meters at Batian peak, making it Africa's second-highest mountain after Kilimanjaro. The mountain is an extinct stratovolcano that last erupted approximately 2.6 million years ago. Seventeen glaciers remain on the mountain, though they have retreated substantially since the first measurements in 1899 when the Lewis Glacier covered approximately 0.4 square kilometers compared to 0.07 square kilometers in 2021. The mountain has three main peaks: Batian (5,199 meters), Nelion (5,188 meters), and Point Lenana (4,985 meters). Batian and Nelion require technical rock climbing skills to summit, while Point Lenana is accessible to trekkers without climbing equipment. The Kikuyu people call the mountain Kirinyaga, meaning "mountain of brightness," and considered it the dwelling place of their deity Ngai. Permanent snow and ice exist above approximately 4,500 meters, though this threshold has risen over the past century.
The Aberdare Range runs parallel to Mount Kenya approximately 60 kilometers to the west, extending 160 kilometers north to south. The highest point is Ol Doinyo Lesatima at 4,001 meters. The range receives heavy rainfall exceeding 2,500 millimeters annually on eastern slopes, creating dense montane forest and bamboo zones that feed the Tana and Athi rivers. Moorland vegetation dominates above 3,000 meters, characterized by giant groundsels, lobelias, and tussock grasses. The Aberdare ecosystem hosts elephants, leopards, and the rare bongo antelope. The eastern slopes drain into the Tana River, while western slopes feed tributaries of the Ewaso Ng'iro River.
Mount Elgon, a massive extinct shield volcano, straddles the Kenya-Uganda border west of the Rift Valley. The caldera measures eight kilometers in diameter, one of the largest intact volcanic calderas in the world. The Kenya side reaches 4,321 meters at Koitoboss peak, while the higher Wagagai peak (4,321 meters) lies on the Uganda side. The mountain formed between 24 and 12 million years ago and once stood higher than Kilimanjaro before erosion reduced its summit. Salt-bearing caves on the lower slopes attract elephants, buffaloes, and other mammals that excavate the walls with their tusks to obtain minerals, creating caverns that extend over 200 meters into the mountainside. The Sabaot people inhabit the Kenyan slopes and have lived on the mountain for at least four centuries.
Lake Victoria forms Kenya's western border, though the country controls only six percent of the lake's 68,800 square kilometer surface area. The lake extends primarily into Uganda and Tanzania. The Kenyan section includes Winam Gulf, a shallow embayment extending 50 kilometers into Nyanza Province. Water depth in the Kenyan sector averages 40 meters compared to the lake's maximum depth of 84 meters in Ugandan waters. Kisumu, Kenya's third-largest city with approximately 610,000 residents, occupies the northeastern shore of Winam Gulf. The lake level fluctuates seasonally by up to 1.5 meters, with highest levels in June following the long rains and lowest levels in February. Water hyacinth, an invasive species from South America, first appeared in Lake Victoria in 1989 and by 1998 covered over 200 square kilometers of surface area, though control programs have reduced coverage.
Lake Turkana, located in Kenya's northern region, extends 290 kilometers from north to south with a maximum width of 32 kilometers. The lake contains 7,560 cubic kilometers of water despite an average depth of only 30.2 meters due to its large surface area of 6,405 square kilometers. This makes it the world's largest permanent desert lake and the world's largest alkaline lake. The Omo River entering from Ethiopia provides 90 percent of the lake's inflow. Lake levels have fluctuated dramatically over millennia. Between 9,000 and 5,000 years ago, the lake stood 75 meters higher than present levels and drained northward into the Nile system. The lake has no surface outlet and loses water only through evaporation, which exceeds 2,300 millimeters annually. Salinity measures approximately 2,500 parts per million, roughly one-third of seawater. The lake contains Nile crocodiles exceeding five meters in length and supports populations of Nile perch weighing over 90 kilograms. Central Island in the southern section contains three active volcanic craters filled with smaller alkaline lakes.
The Chalbi Desert occupies approximately 100,000 square kilometers in northern Kenya east of Lake Turkana. This region receives less than 200 millimeters of precipitation annually, making it Kenya's driest zone. Summer temperatures exceed 40 degrees Celsius, while winter nights can drop below 10 degrees Celsius. The desert floor consists primarily of bare rock, gravel plains, and ephemeral salt pans that fill temporarily during rare rainfall events. The Gabbra and Rendille peoples maintain pastoral livelihoods in this region, moving livestock between scattered water sources. The desert formed through rain shadow effects created by the Ethiopian Highlands to the north and east, which block moisture-bearing winds from reaching the area.
The Tana River originates on the southwestern slopes of Mount Kenya and flows 1,014 kilometers before emptying into the Indian Ocean north of Malindi. This makes it Kenya's longest river. The river drains approximately 100,000 square kilometers, about 17 percent of Kenya's total land area. Flow varies seasonally from less than 50 cubic meters per second during dry periods to over 1,600 cubic meters per second during flood events. Seven hydroelectric dams operate on the river, with the largest being the Masinga Dam completed in 1981, which created a reservoir with 1,560 million cubic meter capacity. The lower Tana region contains Kenya's largest riverine forest ecosystem, covering approximately 13,000 hectares. The river delta region supports mangrove forests and provides critical habitat for the critically endangered Tana River mangabey and Tana River red colobus monkeys, both endemic to this floodplain.
The Galana River forms from the confluence of the Tsavo and Athi rivers in Tsavo East National Park and flows 390 kilometers to the Indian Ocean near Malindi. During the dry season, long sections of the riverbed contain no surface water, with flow persisting only in isolated pools. The river cuts through Yatta Plateau, the world's longest lava flow at 290 kilometers, which formed approximately 13 million years ago from eruptions in the Ol Doinyo Sapuk area. The river channel exposes red Precambrian basement rocks dating to over 600 million years ago.