The permanently swampy core of Lukanga covers roughly 1,850 square kilometres. Add in the river mouths that feed it, particularly the Lukanga River arriving from the northeast, and another 250 square kilometres of flooded channels. Throw in the Kafue River floodplains along its western and northwestern edge, and the whole wetland system reaches about 2,600 square kilometres. From above, in NASA imagery, the swamp reveals a two-toned pattern: dark spots where lagoons like Lake Chiposhye and Lake Suye break through the vegetation, and green-black expanses where thick papyrus covers the water entirely. Near the Kafue channels, the papyrus thins and the swamps read darker still. The wetland sits within the Zambezian flooded grasslands, one of the great seasonal ecosystems of southern Africa.

Fishing is the livelihood here, and it fluctuates with the rains. Older estimates put catches in the thousands of tonnes; a more recent report records about 1,200 tonnes, with declining totals blamed on over-fishing. That pattern repeats across African wetlands: a resource that once seemed inexhaustible runs thinner as boats and nets multiply and nearby roads make markets closer. The Great North Road, the main artery between Lusaka and the Copperbelt, passes within 10 kilometres of Lukanga's southeastern floodplain. That proximity has pulled the swamp into a wider economy. Small commercial farms work its edges. Larger plantations on the northern side have installed dry-season irrigation, drawing on the water the wetland has been quietly storing for millennia.

The circular geometry is what drew impact researchers in the first place. Round wetlands in the middle of continents are rare, and a meteorite crater would explain the shape neatly. But a crater has a signature: shocked quartz, shatter cones, specific mineral transformations in the surrounding rock. The 2002 study found none of these. Some geologists have proposed that the basin is tectonic, a subsidence pocket shaped by the faulting that defines so much of central African geology. Others suggest a drainage-reorganisation origin, with the Kafue River's long floodplain interactions carving the rough outline over geological time. The honest answer in the scientific literature remains: origin unknown. That uncertainty, in a world where almost every landscape has been categorised, is itself a kind of attraction.

Lukanga is listed under the Ramsar Convention, the international treaty protecting wetlands of global significance. It is also an Important Bird Area. Wattled cranes, pelicans, African fish eagles and countless waterfowl use the lagoons and papyrus beds as breeding, feeding, and resting grounds. Hippos and crocodiles populate the deeper pools. In the wet season from November through March, the whole system swells and the distinction between river, floodplain, and swamp blurs; in the dry months, the waters retreat and exposed mud draws wading birds by the thousands. The swamp is quieter than the Okavango, less visited than the Bangweulu, less celebrated than the Luangwa floodplain. But it is a reminder that Africa's wetlands are not only its famous ones. Some of them are simply vast, circular, and unexplained.