Trekking

1. Kalakkadu - Mundathurai
Location:Tirunelveli District, Tamil Nadu
Famous: Wildlife Sanctuaries And Trekking Spots
Best Time To Visit: October To JanuaryKalakkadu Wildlife Sanctuary

http://www.indiainfoweb.com/tamil-nadu/trekking/kalakkadu-mundathurai.html

2.ELAGIRI HILLS
Location: Near Chennai, In The Eastern Ghats, Tamil Nadu
Ideal: Picnic Spot
Famous For : Trekking

http://www.indiainfoweb.com/tamil-nadu/picnic-spots/elagiri-hills.html

3. Adventure Trails

http://www.travelmasti.com/domestic/tamilnadu/adventuretourism.htm