The Sudd is what happens when the world's most famous river gets lost. After leaving behind the Nimule rapids and the city of Juba, the White Nile enters an almost perfectly flat clay plain and, quite simply, stops being a river: it splits into dozens of branches, tangles itself in four-metre papyrus, forms lagoons, channels that open and close from one year to the next, and islands of floating vegetation that can reach thirty kilometres in length. That maze of water and green, which in flood exceeds 130,000 square kilometres and covers around 21% of South Sudan, is the Sudd.
Its name isn't poetic: it comes from the Arabic sadd, “barrier”. For millennia that is exactly what it was. The pharaohs never got through it. An expedition of Roman soldiers sent by Nero around the year 61 was stopped in front of it. Only in 1839-1842 did the river expeditions sent by Muhammad Ali of Egypt manage to force a way through, and with that passage began the European race for the sources of the Nile — and also the spread of the ivory and slave trade into the heart of the continent. Few geographical features have shaped the history of a region so much.
Today the Sudd is also three more things. It is one of the planet's great wetlands, protected by the Ramsar Convention since 2006 with 5.7 million hectares. It is a wildlife sanctuary with shoebills, Nile lechwe and a migration of more than a million hoofed animals. And it is a place of crisis: the states it covers — Jonglei, Unity and Upper Nile — were the hardest hit by the civil war and, since 2019, by floods on a scale nobody can remember. This guide explains what the Sudd is and why it matters, without suggesting at any point that it is somewhere you can travel to today.
The Sudd is the obstacle that kept the source of the Nile in the realm of myth for more than two thousand years. The ancient Egyptians never managed to get past it; around AD 61, an expedition of Roman soldiers sent by the emperor Nero was halted at the swamp, unable to go further; and European maps kept drawing the upper basin blind until the 19th century. The barrier only gave way between 1839 and 1842, when the Ottoman naval officer Salim Qapudan, commissioned by Muhammad Ali of Egypt, led three river expeditions that crossed it and reached first Bor and then Gondokoro — next to present-day Juba — in January 1841. They did not find the sources, but they opened the Nile to navigation from Khartoum to the deep south, and in doing so unleashed the expansion of the ivory and slave trade and, later, British exploration. Ever since, the history of the Sudd has been a tug of war between those who see it as a hydraulic obstacle to be fixed — the Jonglei Canal, dug between 1978 and 1984 and abandoned unfinished — and those who see it as one of the most valuable and fragile ecosystems in Africa.
Read the full history ↓The largest wetland in the Nile basin and the river towns around it: the unfinished Jonglei Canal, Malakal and the Shilluk kingdom, and Bor, where the second war began.
Read the history of The Sudd and the northern Nile →No exact prices: a scale from $ (budget) to $$$$$ (luxury), with 2-3 options per category.
Origins, formation and what the sources say.
The Sudd is neither a lake nor a river: it is what happens when a huge river meets a plain with no slope. The White Nile arrives from the south as the Bahr el Jebel, the “mountain river”, carrying water from the great equatorial lakes and the highlands of Uganda. After the Nimule rapids and past Juba, it enters a plain of black clay covering tens of thousands of square kilometres, almost perfectly flat. With so little gradient, the water doesn't flow. It spreads out.
The result is a graded mosaic. There are open-water channels with submerged vegetation and bands of floating vegetation along their edges. There is seasonally flooded woodland, there are rain-fed and river-fed grasslands, and there is floodplain scrub. All of it shifts every year. The water level rises and falls by up to a metre and a half between the dry season and the flood, and as it moves the banks move with it: new channels open and others close.
The dominant plant is papyrus, Cyperus papyrus, which can live with up to a metre and a half of water above it and forms continuous stands four or five metres tall. Historically it grew alongside water cabbage, Pistia stratiotes, which has now been largely displaced by water hyacinth, an invasive species that makes the blockages worse. When these masses break loose, drift and fuse together, they form floating islands that can reach thirty kilometres in length and block a channel completely.
The water balance is the figure that explains all of Nile politics: around 55 % of the water entering the Sudd is lost to evaporation and transpiration before it leaves to the north. The wetland is also extremely sensitive to what happens upstream. Between 1961 and 1963, a jump in the level of Lake Victoria doubled the flows measured at Mongalla and multiplied those at Malakal by one and a half. The surface area of the swamp grew two and a half times. That episode, documented more than sixty years ago, is the proof that the Sudd breathes in time with the great lakes.
The name says it all. Sudd comes from the Arabic sadd, “barrier” or “obstruction”, and for most of recorded history that is exactly what it was: the plug that kept anyone from reaching the source of the most important river of the ancient world.
The ancient Egyptians, who depended entirely on the Nile's annual flood, never managed to get through it. The geography of the upper Nile stayed in the realm of myth and guesswork. Around the year 61 AD, according to classical sources, the emperor Nero sent an expedition of Roman soldiers upriver to find out where the Nile began. The expedition failed to get past the Sudd and came back with news of an impassable swamp. For fifteen hundred years, Ptolemy's maps and his “Mountains of the Moon” remained the best hypothesis available.
The problem wasn't only the size. It was that the obstacle kept changing. A channel that was navigable one season could be blocked by a floating papyrus island the next. No map was possible because the terrain rearranged itself. On top of that came the heat, malaria, mosquitoes and a complete lack of dry ground to camp on during days of travel by boat.
The barrier gave way in the 19th century, and not out of scientific curiosity but imperial ambition. Muhammad Ali, the ruler of Egypt who had conquered Sudan in the 1820s, ordered the Ottoman naval officer Salim Qapudan to force a passage. Between 1839 and 1842, Salim led three river expeditions. The first left Khartoum in November 1839, with a Sudanese man, an Egyptian official and French engineers on board, and got as far as Bor. The second set out in November 1840, accompanied by a German and two Frenchmen, and reached Gondokoro, next to present-day Juba, in January 1841. Neither found the sources, but they ruled out many mistaken theories and, above all, opened the Nile to navigation from Khartoum to the heart of the continent.
The consequences were enormous, and not all of them good. Opening the river unleashed the expansion of the ivory trade and, with it, the slave trade, run by Ottoman-Egyptian officials and by multinational traders who settled in the region. That same infrastructure later carried the British explorers (the Bakers, Speke and Grant, and later Charles Gordon as governor of Equatoria) and, finally, the colonial carve-up.
The Sudd is not empty. It is the historical homeland of the great Nilotic peoples of the south: the Dinka, the Nuer and the Shilluk, whose societies are built entirely around the yearly cycle of water and cattle.
The system works like this. In the rainy season, from April or May to November, the water rises and families withdraw with their cattle to higher ground, where they grow rain-fed sorghum and millet. When the water starts to recede, from December onwards, it uncovers the tender grasslands known locally as toic, and the cattle camps move down to them. It is a back-and-forth transhumance set by the river, repeated for centuries, and the Ramsar documentation identifies it as the socio-economic and cultural basis of the wetland's entire population.
Cattle are not just food. They are wealth, bridewealth, prestige and identity. The camps are the central social institution: hundreds of head of cattle with the families who look after them, and dung fires whose smoke keeps the mosquitoes away and coats animals and people in ash. Fresh and soured milk is the daily food. Slaughtering an animal is a ritual act, not a meal.
The Shilluk, at the northern end of the wetland, also built the most centralised political structure in the region: the Shilluk Kingdom, founded according to tradition by Nyikang in the second half of the 15th century and ruled by a divine king, the reth, whose physical health was considered mystical and directly tied to the prosperity of the people. Its capital, Fashoda (today Kodok), lies on the western bank of the White Nile, not far from Malakal, and was founded as the permanent royal residence by reth Tugø around 1690-1710.
This human geography has a tragic flip side. The same peoples who shaped the Sudd for centuries have been the main actors in, and the main victims of, the violence of the last four decades, in a cycle where national politics, cattle raiding and competition for water and grazing feed off one another.
If 55 % of the water entering the Sudd evaporates before it leaves, the hydraulic conclusion is obvious to anyone living downstream: go around the swamp. The idea, discussed since the early 20th century, became a formal project between 1946 and 1959 under the name of the Jonglei Canal.
The plan was to dig a 360-kilometre canal that would carry part of the White Nile's flow along the eastern edge of the wetland without letting it spread out. The projected gain was between 3.500 and 4.800 million cubic metres a year, an increase of 5 to 7 % in the water available to Egypt. Digging began in 1978 with a gigantic bucket-wheel excavator brought from Pakistan, one of the largest machines of its kind ever built.
From day one the project was politically explosive. For southern Sudan it was a decision made in Khartoum and Cairo about its own land, with the benefits flowing downstream and the costs staying here. Studies and warnings spoke of collapsing fisheries, the drying out of grazing lands that millions of cattle depend on, and changes to local rainfall, as well as the impact on the wetland's wildlife.
In 1984, with 240 of the 360 kilometres already dug, the Sudan People's Liberation Army halted the work. The excavator was left abandoned in the middle of the savannah, where it still stands. The canal was never resumed, and its unfinished route is today one of Africa's most telling industrial ruins: a 240-kilometre trench and a stalled machine that sum up, better than any speech, the relationship between northern and southern Sudan in the 20th century.
The idea, however, is not dead. Every so often it resurfaces in regional discussions about Nile water, with Egypt and Sudan as the long-standing interested parties. And every time it does, the underlying question comes back with it: what happens to an ecosystem the size of a European country, and to the millions of people who live off it, if you take its water away?
On 5 June 2006, World Environment Day, Sudan's Minister of Environment and Physical Development announced the designation of the Sudd marshes as a Wetland of International Importance under the Ramsar Convention. It was the country's second Ramsar site (South Sudan did not yet exist as a state) and it covered 5.700.000 hectares: 57.000 square kilometres, one of the largest Ramsar sites designated up to that time.
The designation record describes a graded ecosystem, from open water with submerged vegetation to floodplain scrub, by way of floating fringe vegetation, seasonally flooded woodland and rain-fed and river-fed grasslands. It also stresses something technical records usually leave out: that the people living in and around the Sudd are almost exclusively Dinka, Nuer and Shilluk, and that their socio-economic and cultural activities depend entirely on the annual floods and the rains that regenerate the grass on the plains to feed the cattle.
In terms of wildlife, what the designation protects is of world importance. More than 400 bird species, including one of the planet's most important populations of shoebill, estimated at several thousand birds, as well as great white pelicans and black crowned cranes. Some 70 documented fish species. Nile crocodiles and hippos. And an antelope community that includes the Nile lechwe, endangered and found almost only in these wetlands, along with the sitatunga, the white-eared kob, the tiang, the Mongalla gazelle and the reedbuck, with a migration estimated at around 1,2 million animals.
That scale was spectacularly confirmed in 2023. Between 28 April and 15 May that year, African Parks and the government carried out the first comprehensive aerial wildlife survey in South Sudan's history, using two planes fitted with cameras that fired every two seconds and produced more than 330.000 images. The results, covering the neighbouring Boma and Bandingilo parks, were astonishing: close to five million white-eared kob, just under 300.000 tiang, 350.000 Mongalla gazelles and 160.000 reedbuck. Almost six million antelope: by far the largest land mammal migration on the planet, and until then unknown outside the region.
The three states that cover the Sudd (Jonglei, Unity and Upper Nile) saw the worst of the South Sudanese civil war that broke out in December 2013. Malakal changed hands twelve times between 2013 and 2015 and was destroyed. Bor was fought over again and again. The war reshaped the wetland's human geography: hundreds of thousands of people took refuge in UN bases, on islands in the swamp or across the borders.
Then came the water. Since 2019, exceptional rainfall and inflows have pushed the Sudd to levels beyond living memory, a phenomenon researchers attribute to a combination of an anomalous Indian Ocean Dipole, El Niño and climate change, made worse by releases from Ugandan dams on the Nile to protect the shores of Lake Victoria. Between 2020 and 2022, around 2,6 million people in South Sudan were displaced by conflict and floods combined. In 2021 alone, floods affected about 1,2 million people, displaced more than 300.000 and caused economic damage estimated at 671 million dollars. Jonglei, Unity and Upper Nile accounted for three-quarters of those affected.
What sets this apart from earlier floods is that the water never left. Entire villages have been underwater for years, protected by earth dykes built by hand, and some researchers have suggested that the Sudd may be the first case of a population permanently displaced by climate change.
The political situation doesn't help either. The 2018 revitalised peace agreement was never fully implemented, and in March 2025 the house arrest of First Vice President Riek Machar, following clashes in Nasir, in Upper Nile, and on the outskirts of the capital, left the process at its most fragile point, according to the agreement's own monitors. Foreign ministries responded with their highest alert levels: Level 4 “Do Not Travel” from the US State Department, “advises against all travel” from the British FCDO in its guidance of 26 May 2026, and “se desaconseja el viaje bajo cualquier circunstancia” (travel is advised against under any circumstances) from Spain's Ministry of Foreign Affairs, which explicitly names the states of Unity, Upper Nile and Jonglei.
And yet the Sudd is still there, breathing in time with Lake Victoria, with its papyrus, its drifting islands, its shoebills and its million antelope. It is at once Africa's largest wetland, a central chapter in the history of exploration, the key to a water dispute involving more than a hundred million people downstream, and the home of peoples who have read its flood calendar for centuries. The open question is whether the country it belongs to will ever achieve the stability it needs to protect it, and to show it to the world.
