While the online travel giants tussle for their share of flight and hotel bookings, a host of new generation sites are looking to sell travellers their definitive overseas experiences before even leaving the country.

Several colourful and inspirational sites have emerged, enticing consumers to book a ballooning, kayaking or light plane trip online - rather than the traditional method of using a guidebook or stumbling across the requisite roadside stall/beach shack while on holiday and being spontaneous.

"Think how galling it would be to go on a once-in-a-lifetime holiday then find out you missed out on this great experience because you never knew it was there. You can't just rely on the hotel concierge." That's the argument from Ranjan Singh, co-founder of the latest "travel experiences" site to launch, Isango.

Fancy a helicopter trip to go wine tasting in the Hunter Valley? Or perhaps a day swimming with dolphins in New Zealand? These and other travel excursions, tours, trips and experiences are being sold on Isango, which hopes to become the largest repository of the trips and tours that travellers take on holiday.

The activities look like a lot of fun, but personally I like to leave a little up to chance when I'm away. I've got nothing against a bit of forward planning, but heading off on holiday with an armful of print-outs confirming various activities means your holiday "highs" are predetermined - you could even write your postcards before you go.

But Singh, who has previously worked for Ebookers and Expedia, says he sees a gap in the market: "I went to New Zealand in 2004, and while booking the flights and hotels was easy, when it came to demystifying the destination and booking experiences, like a helicopter tour over the Fox Glacier, I had to rely on a credit card payment on an amateurish site, so I was never sure it was actually booked."

But who says you need to book before you go? Popular activities may sell out and to avoid disappointment when you get there, it's probably wise to follows Singh's advice, but a wine tour in South Africa? A Paris river cruise? Why not join the one that takes your fancy when you're there?

At the moment Isango has around 1,000 products, all in long-haul destinations such as Australia, Chile and South Africa. It is simple and colourful with inspirational images and products organised by destination and type, allowing users to search for romantic experiences in Mexico, for example, or scuba diving in the South Pacific.

Singh says the company uses only reputable suppliers, all of whom it has worked with extensively in the past, and adds that in most cases money from its customers filters down to the local community. He also says that around 1,000 products will be added to the site each month, so customers can expect a broader range of experiences every time they visit the site.

The site offers a price match guarantee, charges no credit card fees and allows refunds or exchanges, at no charge up to three days before the booking. Although customer service is a priority, Singh says there is no phone helpline, just a "live chat" facility on the website. This, and the trouble of getting consumers familiar with the unusual name (it means "gateway" in Zulu), will be among the site's greatest challenges.

Isango reflects the trend to increasing sophistication of websites offering travel products abroad. Five years, ago an add-on "experience" was mostly UK-orientated, with firms like Red Letter Days offering racetrack or quad bike days.

Isango has competition from Black Tomato, which sells the entire trip, packaged or bespoke, based around travel experiences, such as elephant polo in Nepal, or a great white shark dive in South Africa. There's also Viator, an Australian firm that currently has the edge on Isango in terms of breadth of content, with over 4,500 tours, sightseeing, activities and attractions across the world.

The bigger companies are also looking to supplement flight and hotel products with "add-ons". Lastminute.com wants to become a "lifestyle portal", selling theatre tickets, dinner reservations and tours alongside holidays and shortbreaks.

The success of these sites will depend on how much people want to itinerise their trips. Rather ironically, the sort of travellers who are expected to book "travel experiences" through sites such as Isango, are those who've shunned package breaks in favour of independent travel.

Ostensibly, they're now creating packages online, filling each spare moment of their holiday, and leaving little to chance discoveries once they get there - but isn't that the spirit of independent travel?