The Periyar Wildlife Sanctuary is spread across 777 km2 (300 sq mi), of which 360 km2 (140 sq mi) is thick evergreen forest. The Wild Life Sanctuary was declared a Tiger Reserve in 1978. The splendid artificial lake formed by the Mullaperiyar Dam across the Periyar River adds to the charm of the park. The greatest attraction of Periyar are the herds of wild elephants that come down to drink in the lake. Sanctuary can be accessed through a trekking, boating or jeep safari.