The 129 ha Koodankulam lake gives its name to the village, as kulam means a lake in Tamil. Koondakulam receives water from the Manimuthar canal and lies to the western side of the village. This lake and neighbouring waterbodies like Kandankulam, Ilamalkulam, Sungulam and Vijayanarayanam lake are brimming with fish and other small aquatic life after the monsoons and serve as feeding ground for waterfowl.
The avian visitors to the lake include painted storks, spot-billed pelicans, egrets, Eurasian spoonbills, blackcrowned night herons and flamingoes. These birds arrive in November-December every year and their nesting homes are in almost every neem and tamarind tree in the village. At times they are even found on the low-slung prosopis trees. All the species of birds that come here can be easily spotted in the village except for the grey herons and the spoonbills which home on the trees on the farther side of Koodankulam tank. Hundreds of grey pelicans, spoonbills and darter birds nest on Acacia nilotica trees on the Koodankulam lakeside.