Gal Oya National Park is popular not only for being home to numerous mammals but also for the largest reservoir in Sri Lanka which is known as Senanayaka Samudraya. Located about 300 kilometres away from Colombo this national park was opened in the year 1954. You will be able to see elephants, Sri Lankan deer, leopards, wild boars, axis deer, muntjacs, toque monkeys, and a variety of bird species as well!