Kantale Tank, one of the biggest and most ancient reservoirs in Sri Lanka, is located in Trincomalee district along the Trincomalee – Kandy Main Road at Kantale, a small town inhabited by a mixed population of Sinhalese, Muslims and Tamils. There are some folk tales on who built this ancient reservoir. Some believe that it was built by Kulakkoddan (an Indian King). However, Mahawamsa, the ancient chronicle records that the Kantale Tank (referred to as "Gangathala Vapi") was built by King Aggabodhi II (604-614 AD). King Parakramabahu the Great (1153 - 1186) further renovated and developed this tank.
Kantale Tank covers a total of 3,750 hectares. The height of the dam is 18 meters and the length is around 2300 meters. The catchment area is 216 sq. km while its water capacity is around 135 million cubic meters. Kantale tank is fed by the longest river Mahaweli and gives water for a large extent of paddy and sugar cane cultivation, which is the the major livelihood of the population in the district. Kantale Tank also gives water for human consumption in and around the district.