Anawilundawa Sanctuary is one of the 6 RAMSAR wetland in Sri Lanka, The sanctuary covers 1,397ha lying between the costal line and the Negambo – Putlam railway line. This wetland consist of six large man made tanks and 3 peripheral tanks interconnected to create a complex irrigation system. The larger tanks are Pinkattiya, Maradansola, Anawilundawa, Mayyawa, Surawila and Vellawali.

The history of these tank system goes back to 12th century and sadly the water ways which fed this system is lost without an trace and today these tanks are fed by flood waters of the Deduru Oya brought to the area via the Sengaloya scheme. These tanks has created a natural habitat which is ideal for the birds as well as supplied water to paddy fields around this area for over 800 years.

Today this area is very popular among bird watchers and nature lovers. During migration season a large variery of birds can be seen using this area as feeding ground as well as breeding ground.