The lake (or merja in Arabic) of Sidi Boughaba is a remarkable protected site for the preservation of biodiversity. It is one of the remains of the last wetlands (freshwater swamps) on the northwest coast of Morocco. The mist sometimes makes the landscape a little unreal, especially when it is thick. It comes from the Atlantic Ocean from which it is only separated by a high dune.
At the mouth of the Sebou River in Mehdia, the lake lies southwest-northeast, parallel to the Atlantic coast.
There are more than 171 species of birds, the majority of which only winter, the rest nesting there regularly. The lake is located on a migration route. The birds go to feed in the lake, others at the seaside. The species observed, among others, are marbled teals, crested coots, great crested grebes, pink flamingos, northern shovelers and marsh harriers. . A significant population of partridges stays there as well as the rest of the migratory or sedentary passerines. Due to this diversity and function, the Reserve falls under the Ramsar Convention.