The Tsavo River is a waterway in southeastern Kenya that runs east from the western end of Tsavo West National Park, near the Tanzanian border, until it joins the Athi River to form the Galana River near the center of the park. The river is the main contributor to the watershed of the lower portion of the park region and supports abundant fish, as well as crocodiles, hippos, and cape buffaloes along its banks. Its name derives from the Maasai word for 'slaughter,' referencing a historic battle between the Maasai and Kamba tribes at this location roughly five hundred years ago. The river is most notorious, however, as the setting of the 1898 Tsavo Maneaters incident, when a pair of lions terrorized workers constructing a railway bridge at this crossing. Gates traveled approximately 132 miles from Mombasa — retracing the route Colonel J.H. Patterson made in 1898 — to stand at the infamous Tsavo Bridge and investigate what really happened that year.
A fierce battle between the Maasai and Kamba tribes takes place near the river crossing, giving the site its name — 'Tsavo,' meaning 'slaughter' in Maasai.
Construction of the Uganda Railway begins; the project spans roughly 600 miles of East African wilderness at a cost equivalent to approximately one billion dollars today.
Colonel J.H. Patterson arrives to supervise construction of a bridge over the Tsavo River. Two man-eating lions begin attacking and killing railway workers, in what becomes one of history's most documented lion attacks.
Josh Gates investigates the Tsavo Maneaters incident with Field Museum curator Julian Kerbis Peterhans in Expedition Unknown S15E02, 'The Man-Eating Lions of Kenya.'
Julian Kerbis Peterhans, a curator at Chicago's Field Museum and one of the leading scientific authorities on the Tsavo Maneaters, joined Gates on location at the Tsavo Bridge. Peterhans has spent years studying the two lions responsible for the 1898 attacks — whose remains are preserved at the Field Museum — and was on hand to help Gates assess how much of Colonel Patterson's famous account, published as a book that became the main source of information about the killings, holds up to scrutiny. When Gates asked whether he should worry about being eaten by a lion in present-day Tsavo, Peterhans answered plainly: "Yes. You should always be wary. We have a good lion population. We don't mess around at night."
The 1898 Tsavo Maneaters incident unfolded during construction of the Uganda Railway, a British imperial project that Patterson himself described — and Gates echoed — as laying tracks across 600 miles of untamed wilderness at an enormous cost. The Tsavo River crossing was one of the most demanding sections of the route. Mainstream historical and zoological research has confirmed that two male lions — unusual for lacking manes — killed a significant number of workers over several months before Patterson shot them. The exact death toll has been debated for over a century, with estimates ranging widely; scientific analysis of the lions' remains has helped researchers refine those figures in recent decades.
What makes the Tsavo Maneaters scientifically compelling — beyond the sheer drama of the story — is what they reveal about lion behavior. Researchers have examined isotopic evidence in the lions' bones and teeth to estimate how many humans each animal consumed, and the findings suggest the attacks were more prolonged and calculated than a simple opportunistic predation event. Whether injury, disease, or environmental pressure drove the lions to target humans remains a subject of genuine debate among wildlife biologists.
Gates' episode frames the investigation as an effort to separate documented history from the mythology that built up around Patterson's self-aggrandizing account. The show explores whether the events unfolded as Patterson described, consulting Peterhans as the on-camera scientific voice. The episode does not claim to resolve every historical question about the death toll or the lions' motivations, but it grounds the story in the actual landscape — the river, the bridge, the terrain — in a way that Patterson's original narrative, written for a Victorian audience hungry for adventure, understandably did not.
The name 'Tsavo' derives from a Maasai word meaning 'slaughter,' referencing a battle between the Maasai and Kamba tribes that took place at this location approximately 500 years before the famous lion attacks.
The Tsavo River joins the Athi River to form the Galana River near the center of Tsavo West National Park.
The Uganda Railway — which the Tsavo Bridge was built to carry — stretched roughly 600 miles and cost the equivalent of approximately one billion dollars in today's money, earning it the nickname 'the lunatic line' among skeptical British taxpayers.
The two man-eating lions killed in 1898 were both male and notably maneless — an unusual characteristic that has fueled ongoing scientific interest in Tsavo's lion population, which still exhibits this trait today.
The Tsavo River and the area around the historic bridge are accessible via Tsavo West National Park, which generally requires park entry fees and is best navigated with a local guide or organized safari operator. The nearest access point for independent travelers is the town of Voi, approximately 32 miles from the bridge site. Visitors should be aware that Tsavo is active lion country, and travel within the park after dark is strongly discouraged — check current park advisories before visiting.
Voi, Kenya, approximately 32 miles from the Tsavo Bridge site; Mombasa is roughly 132 miles to the east.
The dry seasons — roughly June through October and January through February — offer the best wildlife viewing and most accessible road conditions. The rainy seasons can make dirt tracks in the park difficult to navigate.
Tsavo, Kenya
Tsavo town and its surrounding national park form the broader landscape of the 1898 Maneaters investigation Gates pursued in S15E02.
Voi
Voi is the nearest town to the Tsavo Bridge and the point from which Gates departed by road to reach the river crossing in the same episode.
South Africa (Kruger National Park region)
Kruger National Park represents a comparable southern African wilderness context involving big game and human-wildlife history, appearing elsewhere in the Expedition Unknown database.
Historical data sourced from Wikipedia