1. A cross-country bike ride: I don't really know if there is some such term. I haven't had any such ride as yet. But from all I know about bikes, rides and me, I'd definitely take one soon. For all those who love bikes and riding them, I don't need to explain what I mean.
For the rest of the lot, if you've ever enjoyed a pillion ride, it's about time you go one step ahead and try your hand and you'll see what I mean by this. Select a duration of around a 2-3 days, select a route, have a decently serviced and reliable bike, have your protective gear (helmet, gloves, shins) and off you go. Take a few pals along and you'd remember it for the life.
2. Go Rafting: If you've ever seen a commercial or a movie featuring a bunch of youngsters hitting a rough river in an apparently rubbery looking raft and having a gala time while flirting with the dangerous tosses the river gives, you've just seen what is called white-water rafting.
Having been there, done that before, I can say with a fair amount of confidence that it is one of the most thrilling adventure. And what's more, there are loads of good rafting-stretches in our country with few of the best rapids. Have a look http://thrillophilia.travellerspoint.com/1/
What's more, a rafting stretch encompasses wonderful scenic locations, loads of calories burnt, a good tan, opportunity to trek and an experience to cherish and share.
3. Rock climbing and rappelling: Again something that looks awe-inspiring if you've seen movies like MI-2 or Lakshya. All the more lovelier and exciting if you do it. Having had a really light bit of stint with it, I'm left wanting for more. The feeling of having tried the cliffhanging experience for a very short time, I really look forward to more of it.
India again provides umpteen number of destinations for such endeavors. The Himalayas, the Eastern and the Western ghats and many other mountains provide rock climbing and rappelling opportunities with a flock of adventure sports companies giving you a great chance of getting a hang of it.
So put your best foot forward (although better get it clad in the best hikers you can lay your hands on).
4. A trip to Kashmir: Well, some poet or king, despite his greatness, whose name I forget, once said that if there is a heaven on this earth, it's right here in Kashmir..
I second him. One of the most scenic and enticing places on the face of this earth, there is hardly anyone who hasn't thought of going there. And what's more, there are even more reasons to be going there in winters when the cold is chilliest and yet the romanticism of the place is at its peak.
Going to Kashmir and getting enchanted by it's valleys, lakes, mountains, snow, people, gardens and all kind of beautiful things is even more a thing-to-do when you are pretty young because you'd be able to go a few meters ahead of everyone else and feel the bliss a few shades higher. You have to be there and do it to know what I mean.
Advice: If you've parents or family members back home who haven't been there, take them along. You'd not repent it.
5. Find out a marine sanctuary and visit it: A marine sanctuary would be something not many people in India would take as an exciting place to visit. With all due respect to all of them, I disagree.
Select a nice long weekend, ideally at the end of the monsoon and go give a two-day visit to some such marine-life reserve. It would ideally be a small island not very far from the land mass or an insular region with lesser access to human activities.
The visit would have a lot of marine life spotting. In addition to it, although, it would have experiences like living by the coast in a tent, living without electricity for a couple of days, being the first person to set your footsteps on the tide washed sand in the morning, no mobile network and no chance of spending your money (also termed by a few as shopping).. Some part of it sounds demotivating, doesn't it? It's not.. In fact ask anyone who's done it and they will be all raring to go again given the first chance.
Loads of things you could do at such places would surprise you. It would totally change you and leave you a refreshed person.
6, 7, 8, 9... And the list could continue and still never be comprehensive. Although this post has already started to look like some travel brochure, I hope the point is driven home.
It's lovely being at home, but it's blissful feeling at home with nature. Do it when you are still physically capable at your body and your mind to do it and enjoy it to the fullest.
P.S. Take your pals or family along, but try to have a few people of your age during such trips to multiply your fun-factor. Carrying a nice set of digicams and handycams would only add value to your experience. As they say, there truly is an Incredible India to be explored..