Silent Valley National Park
Silent Valley is considered one of the most ecologically diverse areas on the planet.
In the 1950s, the Kerala State Electricity Board wanted to build a dam across the Kunti river, which flowed in the deep forest. Nationwide protests in India by environmentalists and mass publicity by the media led the then prime minister, Indira Gandhi to order the state government to abolish the hydroelectric project. The area was declared a National Park.
The park is actually named Indira Gandhi National Park, and Silent Valley is the name of the place, but it is also called Silent Valley National Park. It is a wonderful place to visit for tourists.
Tropical evergreen forest. Huge trees, thick undergrowth. Heavy rains during the monsoons. Shola grasslands higher up.
 Flora and fauna
Lion tailed macaque, elephant, leopard, tiger, nilgiri thar, malabar giant squirrel. Variety of other large mammals including deer, gaur etc. Large population of birds like hornbills, malabar whistling thrush etc. The place is teeming with the more "common" birds like drongos, tailorbirds, spotted dove, koels etc.
Humid during the rains (June, July, August), otherwise generally hot and tropical.
 Get in
The nearest railway station is Palghat Junction (Palakkad). From Palakkad, go to Mannarkkad, and from there to Mukkali. Both places are well connected by private buses. If you are planning to stay at Mukkali, reserve rooms in advance at the Forest dept resthouse. Or else you can stay at Mannarkkad and hire a jeep to reach Mukkali by 8AM. Mukkali is about 60 km from Palakkad, with Mannarkkad en route. The visit to the Valley and Kunti river will take only a day, and you can return back to Palakkad the same evening.
Another close railway station is Coimbatore Junction. From Coimbatore, take the road to Anakatty(around 30 kms) from Coimbatore and from Ankatty to Agali (15 kms)and then Mukkali(20 kms). The total distance via the Coimbatore route is only around 65kms. Its almost a straight road drive from Coimbatore to Mukkali. The scenic roadway keeps one captivated all through.
Permission is required from the Kerala Forest Department. For a short one day trip (usually taken by tourists), permission can be obtained on the spot at the Forest Department office at Mukkali. This trip includes a short trek of about 2-3 km to the hanging bridge at the Kunti River.
The entry point of the road to the park is Mukkali. From Mukkali, it takes a 30 km jeep ride to get into the actual entry point of the park. Jeeps can be hired from Mukkali. It is difficult for cars to traverse, so don't attempt to drive unless you are adventurous and have an SUV and good skill on mountain roads.
Tourists are not allowed to stay in the valley. They must come back to Mukkali by evening.
Entry into the valley is allowed only from 8AM to 2PM, as you need about one and a half hours (each way) to go to the Valley and come back. The Forest Department deliberately does not allow going to the valley early in the morning to minimize disturbance to the animals. Tourists will not be allowed to stay/camp overnight at the valley.
You will not be allowed to proceed without a guide. A guide will be assigned to your group when you get permission from the Mukkali Forest Dept Office.
If you are just a casual tourist, then this is fine, but serious naturalists will have to contact the Wildlife Warden much earlier and get adequate permission. Trekking in deep forest (for a few days) requires permission from the Forest Department office in Trivandrum, and is difficult to get.
Anyhow, it is almost impossible to get permission to go anywhere near the core of the national park, unless you are a field researcher or something like that.
For Indian citizens, fees are not very high.
Approximately, they are (in May 2010):
 Get around
[add listing] See
Enjoy the thick jungle, see the birds, you are lucky if you see the big mammals (on the short trek). Mostly you will see the Malabar Giant Squirrel, black langurs and of course many kinds of birds. Trek down to the Kunti river. There is also a watch tower overlooking the jungle. The back of the Inspection Bungalow at Mukkali is a great place for bird watching.
[add listing] Do
Take a bath in the Bhawani River at Mukkali.
[add listing] Buy
You can buy lots of natural products in the forest department's own store, including pure original wild honey etc. The prices are nominal.
[add listing] Eat
You have sairandri restaurant at tree top resort,chindakki near silent valley. You have a delicious food from there. And you have some small restaurents at mukkali..
[add listing] Drink
[add listing] Sleep
Forest department has a guest house/dormitory at Mukkali. Rooms have to be booked in advance. Rooms are decent , without expecting anything more than what can be expected in remote outskirts. If your focus is nature, then it shouldn't matter. Ensure you are prepared for power cuts, which are very frequent. The forest guest house is at a good , peaceful place, with the bhavani river just flowing behind the guest house.
Tourists are not allowed to stay overnight at the Valley; they have to return back to Mukkali by evening. So camping in the jungle is difficult. Mukkali is also densely forested; you may ask permission from the Forest deparment office if you wish to camp in Mukkali. No gurantees.
 Stay safe
No much problems. Watch out for leeches in the jungle. Carry table salt from Mukkali to remove leeches from your legs. Even Mukkali is a remote place, so take care of yourself, avoid being flashy in any term. As far as the forest goes, its safe, unless you dont follow the forest rules.
 Get out
Come back to Palakkad to get a train/bus to all parts of India. Nearest airport is Coimbatore, about 120 km away from Silent Valley.
To come back to palakkad from mukkali, there are only a few buses at the check post near mukkali. Check for exact timings with locals, if you dont want to be stranded for the next bus which would be after a few hours.