The park has a lagoon which is fed by brackish water from one of the tributaries of the Senegal river, significant estuarine, saline flats, dunes, mangroves swamps, dunes, alluvial plains, a series of lakes or ponds and a dam.
The vegetation in the park is a combination of Acacia tortilis, A. senegal, Euphorbia balsamifera and Balanites aegyptiaca, with a herbaceous cover of Cenchrus biflorus, Chloris prieurii and Schoenefeldia gracilis. Tree cover is more varied and abundant towards the inland edge of the dunes, with Borassus aethiopum, Acacia nilotica, A. seyal and Parkinsonia aculeata.
There is little cover on the alluvial plains, but Tamarix senegalensis and Arthrocnemum glaucum occur on sandy knolls and Acacia nilotica beside creeks and pools. Herbaceous cover on the lower zones of the plain is dominated by halophytes, such as Salsola baryosma. The grass Sporobolus robustus is common in the most frequently flooded areas. Grasses are more important in less saline areas, with Echinochloa colona and Vetiveria nigritana in depressions and Schoenefeldia gracilis on higher ground.
Some of the birds in the Diawling National Park include pelicans, starling, golden sparrow, gull, Peid avocet, northern pintall, great egret, Euroasian spoonbill, Caspian tern, black scrub robin, Lesser flamingos, black storks, African spoonbill and many other water birds. There are more than 220 birds recorded in the park nesting and breeding at the saline water delta of the Senegal river
Some of the animals in the park include wart hogs, wild donkeys, monkeys and many others.