A wetland is a place that is permanently or seasonally filled with fresh water, salt water or a mixture of these two. As such, wetlands include areas such as marshes, ponds, borders of rivers and lakes and deltas. Though often neglected in environmental conservation programmes, wetlands are one of the most important ecological units of the environment. For instance, wetlands act as natural water filters, trapping metals and other toxic elements in the sediment .
Mauritius is entirely surrounded by seawater. Freshwater sources include reservoirs, rivers, lakes and ponds that cover an area of 435 ha . The water basins, combined with the rugged topography of the island, have given birth to the different types of wetlands as follows:
|Type of wetland||Location||Size (ha)|
|1. Floodplain||inland (such as the banks of rivers and lakes)||62|
|2. Marshes||coastal and inland (transition areas where the land meets the sea and ponds)||240|
|4. Mangrove swamps||coastal||49|
|5. Marine coasts||coastal||118|
144 wetlands falling in the above-mentioned categories have been identified . They cover an area of 1839 ha, concentrating mostly on the east and south-east coasts of the island. This is due to the amount of rainfall that these areas receive throughout the year. Water seeps into the ground and is retained in the soil causing the upper layers to remain moist and overflow. Natural wetlands cover only a surface area of 639 ha; they include marshes and mangrove swamps.
It goes without saying that wetlands play a vital role in maintaining the appropriate environmental balance. They act as sponges during rainfall and absorb water. Mangrove forests protect the shore from waves, tsunamis and help mitigate the effects of climate change.
Many plants such as watercress and songe grow in the muddy areas near river banks. These sites are thus used for commercial and private cultivation of these foodstuffs. Fishes and crustaceans depend on the sediment of mangroves and estuaries as breeding sites; this, in turn, provides food for predators like birds and ultimately humans. The wetlands also have recreational uses such as bird sighting at Rivulet Terre Rouge and kayaking in the mangroves of Ile D’Ambre.
The Grand Bassin basin has religious importance for the Hindu community. It is considered as a sacred lake connected to the Ganges River in India.
In September 2001, Mauritius adopted the Convention on Wetlands to protect and conserve the local marshes and to use them wisely is a sustainable way. Also called the Ramsar Convention (after the city in Iran in which it was first adopted), three sites of international importance covering an area of 401 ha  were nominated: