Amaravathi Dam is a popular spot among adventure seekers. Take a boat ride to the Amaravathi Reservoir, which is surrounded by the Annamalai hills. You can also go for a trek in the hills or try rock climbing. The view from the top is worth all the effort.
Monkey Falls is a set of cascading waterfalls surrounded by lush green forests. You can go for a swim or just relax and enjoy the view. There are also some adventure activities available such as zip-lining and rappelling.
If you have more time, you can also visit the Indira Gandhi Wildlife Sanctuary and National Park, which is a 40 minutes' drive from Monkey Falls. You can also visit the Thirumoorthy Dam and Falls, which is a 30 minutes' drive from Udumalpet. If you have less time, you can skip the trekking and rock climbing at the Amaravathi Dam and just enjoy the boat ride.