You used to know where you were with the Cotswolds. Chocolate-box villages, twee thatched pubs and lots of ageing ramblers marching gamely between them across an undulating and pretty but relatively untaxing landscape.

For a family like mine, keen on mountain biking, rock-climbing and canoeing, it seemed the kind of place to leave swiftly behind as we headed for the mountains of Wales, the Lake District or Scotland.

The Cotswolds, I thought, could wait until I became too old to make it up steep slopes and too scared to freewheel down them.

Recently, however, I was persuaded to cut short my northern journeying and spend a few days in that cuddly heart of England. It was a bit of a shock: the Cotswolds have become rather adventurous.

Take canoeing, for example. One of the Cotswolds’ claims to fame is as the source of the River Thames. It pops out of the ground in a Gloucestershire meadow and then meanders down to London.

It’s always been popular for a little gentle boating but that sounded boring, so we opted for something far more adventurous: canoeing from as close to the source as we could get, right down to Lechlade. That meant a trip of about 14 miles, starting near Cricklade, where the river becomes navigable.

Tim Lloyd, owner of the Riverside pub and marina in Lechlade, who has bought a fleet of tough four-man “KataKanus” especially for the trip, laughed when I told him I’d be taking my children. Tim, 11, and Eliza, 7, on the trip.

The next day, as he hitched the craft to a trailer to drive us to the launch site, he introduced me to Lee, his 6ft, heavily muscled boatman. “Here’s your engine,” he said.

Two hours later, as the current whirled the heavy boat towards another narrow gap between fallen trees, I could see what he meant. I’d expected a slow-moving meandering stream but instead there was a strong current.

Few people bring boats this far up river so there was also lots of overhanging vegetation. I’d have struggled on my own but with two adults it was easily managed and the kids had a great time fending off, paddling and pushing the canoe downriver.

Several hours later we arrived back at Lechlade. Apart from a pub-lunch stop it was the first civilisation we’d seen all day, an amazing tribute to the rural quality of the journey.

After such an epic trip a touch of refinement seemed well-deserved. The Trout Inn, also in Lechlade, is just the kind of traditional pub you’d expect to find in the Cotswolds. Bob Warren, its owner, is concerned at the way the area is changing and the influx of adventure-seeking tourists (did he mean us?), but anybody who serves food as good as his has no need to worry.

The Lower Mill Estate, where we stayed, took us even deeper into old-fashioned Cotswold luxury. It’s a holiday-home development but very traditional in style. Who, however, would want to relax in a beautiful house with a view over lakes and a river when there’s more adventure to be had? Well, me, for one, not to mention my wife. The traditional charms of the Cotswolds were getting to us.

But it was not to be, not with kids around. Just around the corner lay Keynes Country Park near Cirencester, and on it an activity that I really never had expected to find in this area – rock-climbing.

Well, okay, it’s not exactly rocks. Head 4 Heights is actually several 60ft poles stuck in the ground with hand and foot holds to let you climb them. Overhead is a set of cables and belay devices so that you can jump and fall in complete safety.

Reluctantly I tried it, jumping from a tiny platform into thin air. The kids mocked my terrified face as I fell – safely belayed – to the ground. Then they rubbed it in by climbing higher and jumping further.

My pride was, however, restored that afternoon with the cable waterskiing at Watermark Ski in nearby South Cerney, using what appears to be ski-lift technology to run a rotating cable around a lake. By grabbing a handle attached to the cable you can water-ski or wakeboard without a boat to tow you. I took to it straight away, zooming round and round on a kind of wakeboard and even gaining the confidence to carry my daughter on my back.

However, if that doesn’t grab you, then you can just relax and watch the action. The Lakeside Brasserie has been set up to overlook an adjacent lake where there’s real waterskiing. A great meal was only improved by the sight of fellow newcomers getting a good dousing.

By the end of that, though, I’d had enough. I’ve trekked through most of Britain’s hills but I’d never come out of two days’ adventure with so many aching muscles.

You can of, course, still go to the Cotswolds and do nothing more than relax but if you plan to go there looking for adventure, then get fit first. A training week in the Alps should do it.

- Riverside, 01367 252 229, www.riverside-lechlade.co.uk. A day trip down the Thames costs £100, B&B starts at £35 per person/night; Trout Inn, 01367 252 313, www.thetroutinn.com. Meals from about £20 a head excluding drinks; Orion Holidays, 01285 861 839, www.orionholidays.com, arrange accommodation at Lower Mill Estate, near Cirencester, with a variety of properties around four lakes. Three nights in a grade A property start at £322; Head 4 Heights, 01285 770 007, www.head4heights.net. Prices from £5 for a single climb up to £24 for a family package with several activities; Watermark cable ski, 0845 895 9000, www.wmski.com/cable.html. Prices from £15 for an hour to £30 for three hours or more; Lakeside Brasserie, Spring Lake, 01285 860 606, www.watermarkclub.co.uk/leisure/brasserie.htm

www.visitthames.co.uk/familyfun