As of this place is nearby my home town in kerala.,it's seems to have a 80 plus kilometre drive to reach the destination.i can explain this trip you in this way also the places you can cover by this drive(punallur-thenmala-thenkassi).
If you are coming to visit varkala or near Trivandrum you can add this place also to your bucket list because it's just a 100 kilometers from those pin in maps. This route is going towards the other side of boarder sharing with tamilnadu where you can explore the vast natural beauty between Kerala and tamilnadu. Better you can went directly to thenkassi in the early morning because the place called thirimala covil the temple situated a 20 plus kilometre from kerala boarder the early morning view is outrageous.
Please try to reach there before 6am the view is stunning the main part this temple is located at the top of the hill
You can enjoy the traditional architectural part of this temple because the whole temple is made up of pure rock,if you like to have a morning trekking u can step a 100plus stair all along to the hill.
You can also take your vehicle up to the top by paying 50rps.
You can spend about 1 or 2 hours there and can leave back to thenmala there you can find the palaruvi water falls,thenmala eco tourism park,thenmala dam.just in one place back from all the adventures just take a break in punallur there you can find this hanging bridge which is made in tough iron hangers and wood by british.a massive piece of engineering