The Mahaweli River is 335 km (208 miles) long and is considered to be the longest river in Sri Lanka. It has the largest land area of 10,448 km2 (4,034 sq mi) and has a drainage basin covering about one-fifth of the total land area of the island. The actual creation of the Mahaweli River begins in Polwathura (Mahavila area), a remote village in the Nuwara Eliya District on the banks of the Nawalapitiya in the Kandy District. This river reaches the Bay of Bengal on the southwest side of the Bay of Trincomalee.
At 7360 feet, Sri Pada is the fifth highest mountain range in Sri Lanka. It is believed that the four rivers Mahaweli – Kelani – Kalu – Walawe originate from the Sri Pada mountain range. But the origin of the Mahaweli River, the longest river in Sri Lanka, has nothing to do with the Sri Pada mountain range. As part of the Mahaweli Development Program, the river and its tributaries have been dammed for irrigation in the dry zone, covering an area of 1,000 km (386 sq mi). The six dams in the Mahaweli system generate more than 40% of Sri Lanka’s electricity needs. One of the many sources of the river is the Kotmale Oya.
The source of water for the Mahaweli is the Kirigalpotta Horton Plain and the thotupola mountain range. There are several tributaries of the Mahaweli River. They are Nanu Oya, Puna Oya, Pundalu Oya, Kotmale Oya, Hatton Oya, Nilamba Oya, Thalathu Oya, Hulu Ganga, Beli Ul Oya, Kirindi Oya, Loggal Oya
, Uma Oya, Badulu Oya, and Amban Ganga, etc. Boating is one of the most popular activities around this river. These boat rides take you across the flat waters of the Mahaweli River along the beautiful river banks. There you can see reptiles, lizards, bird nests, and monkey tribes.