Mamili National Park formerly known as Nkasa Rupara National Park is named after two broad areas of raised ground in the Kwando Delta, which become islands at the height of flooding. Nkasa Island is located in the south and Rupara in the northeast. The word 'nkasa' is interpreted as 'hippo swamp', and 'rupara' also spelt 'lupala' as 'dry bushes'. The park has the distinction of being the largest wetland area of conservation status in Namibia, characterized by a complex network of channels, reed beds, ox-bow lakes, and tree-covered islands. The focal points are the two large islands of Nkasa and Lupala in the Kwando/Linyanti River. These islands can be reached by road but only in the dry season. After rains, the area becomes flooded, cutting them off from the mainland.

An amazing 430 species of birds have been recorded, which is nearly 70% of Namibia's total, and much game including the rare sitatunga and red lechwe as well as buffalo, elephant, zebra, antelopes, hippo, and crocodiles. This national park is set apart from the rest of the wildlife strip and is thus considered as a secluded part. However, it has to be visited for viewing vast wetlands with swamps.

These tranquil waters are home to many different species of ducks and geese, including the fulvous duck and the African pygmy-goose. The African jacana and the uncommon lesser jacana move between water lilies in search of food. Their exceedingly long toes allow for such a wide distribution of weight that these birds appear to walk on water. The vibrant purple gallinule is seen alone or in pairs, while the lesser gallinule is an uncommon and irregular resident, but a great 'tick' for bird watchers. Nkasa Rupara is open all year. Accessibility may be limited by flooding of the Kwando during winter. Local rains may make tracks impassable in summer. The park is open for day visitors from sunrise to sunset.