Vembannur wetland is a human-made inland tank, spanning around 20 ha and situated near Vembannur, a small hamlet in Rajakkamangalam Block, in Kanniyakumari District. It comes under Melasankarankuzhi Panchayath, located 8 km from district headquarters Nagercoil, 4 Km from Rajakkamangalam &736 km from State capital Chennai, &is near to Bay of Bengal. Vembannur wetland forms the southernmost tip of peninsular India. This wetland forms part of the Important Bird and Biodiversity Area (IBA) and hence part of BirdLife International Data Zone. About 250 species of birds have been recorded in the district. The site hosts around 12% of the total non-breeding population of garganey. Around 5 rare, endemic &threatened flora are present within the Site. The tank is believed to have been constructed in the regime of Pandyan king Veeranarayana. The tank and the Therrakal canal were designed to take water from River Pazhayar for irrigation purposes. The River Pazhayar and Vembannur wetland collects the entire drainage of the valley and irrigates a substantial part of Nanchilwadu.

A wetland should be considered internationally important if it contains a representative, rare, or unique example of a natural or near-natural wetland type found within the appropriate biogeographic region.

A wetland should be considered internationally important if it supports vulnerable, endangered, or critically endangered species or threatened ecological communities.

A wetland should be considered internationally important if it supports populations of plant and/or animal species important for maintaining the biological diversity of a particular biogeographic region.

A wetland should be considered internationally important if it supports plant and/or animal species at a critical stage in their life cycles, or provides refuge during adverse conditions.

A wetland should be considered internationally important if it regularly supports 20,000 or more waterbirds.

A wetland should be considered internationally important if it regularly supports 1% of the individuals in a population of one species or subspecies of waterbird.

A wetland should be considered internationally important if it supports a significant proportion of indigenous fish subspecies, species or families, life-history stages, species interactions and/or populations that are representative of wetland benefits and/or values and thereby contributes to global biological diversity.

A wetland should be considered internationally important if it is an important source of food for fishes, spawning ground, nursery and/or migration path on which fish stocks, either within the wetland or elsewhere, depend.

A wetland should be considered internationally important if it regularly supports 1% of the individuals in a population of one species or subspecies of wetland-dependent nonavian animal species.