Gal Oya serves as the catchment area for the largest reservoir in Sri Lanka called the Senanayake Samudraya. It was established in 1954. The jeep safari through the park is the best way to catch the sights of leopard and elephants. Visitors can also enjoy the boat safari which gives the opportunity to reach the Bird Island located within the reservoir. Triphala, an Ayurveda medicine and the important ingredients are the three herbs, is found in the National park. There are 32 species of mammals and 150 species of birds.