The boat’s outboard splutters to a halt. The waves from the bow fan out ahead and break along the sandy beach. The boat follows behind, gliding towards the bank, the crunch on gravel echoing through the now silent valley as we land. Within minutes I am crouching down, 4- weight in hand, watching five large trout feed in very clear, thin water. I am in Argentina.

Now, I’ve always thought I was good at spotting fish. When not doing the day job I often find myself guiding guests on the River Kennet in Berkshire. It’s my chance to show off to inexperienced, and sometimes experienced, anglers my sighting skills. These moments are highlights of my fishing life: picking out that camouflaged tail swaying in the current below an overhanging willow branch; crying out “Strike!” as a light coloured fleshy mouth chomps on a drifting nymph 10 yards upstream; the words of disbelief, like “How on earth do you see these things?” or: “There must be something wrong with my sunglasses…let me try yours!” It all makes me smile as I reflect on the day during the journey back to London.

Of course, if people spent as many hours as I do on the river, they’d be as good as me. Then again, their busy lives don’t allow the required dedication and time on the riverbank. In theory my life should be the same as theirs but in summer my ambition is usurped by fishing.

Which brings us back to Argentina. The Futaleufu is a huge river running through the highland region of Patagonia that stretches through Argentina and Chile. It is one of the most beautiful and unspoilt fishing regions on earth. The river carves its way through steep canyons, swirling through deep, dark pools, tumbling over rocks or serenely sweeping around large shallow bends covered in golden sand.

I am lucky enough to be staying at El Encuentro Lodge, perched high up on the river bank overlooking at least 40 miles of clear, pristine trout water and all accessible by boat and wading. The lodge has been owned and run by Englishman Michael Beale and his Argentine wife Jane for over twenty years. Their five children - three sons and two daughters - all help with the guiding. Today, I’m with Nicholas, the junior son, whose experience and knowledge belies his young age.

Our boat travelled for just 10 minutes before we reached the bend with the feeding trout. On the way the sun had beat down on our backs and all sorts of ducks and geese had taken flight from the moving boat. Speckled teal, brown pintail, spectacled duck, southern widgeon, ashy headed geese, red shovellers, cinnamon teal, upland geese and the rare flying steamer duck. Many of these birds, along with giant kingfishers and buff necked ibis, had bid us good morning as we ate breakfast on the veranda just an hour before.

The fish were in such shallow water their dorsal fins broke through the surface. I assumed they were feeding on snails - I hoped that they were not in a discerning mood as my small dark nymph plopped down about three feet from them. Surely they would spook in that skinny water? Without hesitation a 3lb rainbow dashed towards the fly like a remote controlled toy submarine.

The line tightened, the rod arched forward and after a splash and a swirl the fish was gone - leaving a slack line in the water. Nicholas sighed in disbelief - the hook was slightly bent and had not struck home. My disappointment at such a frustrating debut on the Futaleufu was short-lived, however; to my astonishment, the remaining fish had settled down within 5 minutes of the earlier commotion and a 21/2 lb rainbow was soon glistening in the sunshine in front of my camera lens.

It was a successful start to the day - but any thoughts that this would be easy fishing were misguided. We moved on up the river; willow trees and lush vegetation lined the banks - it was an ever changing panorama as we turned the bends. One minute vast grey rocks towered above us, the next lush green pastures rolled away over open plains as far as the eye could see.

The sandy bottom of the river, dotted with fallen branches and occasional weed beds, was visible through the deep clear water as it skimmed along below us. Narrow deep channels disappeared away from the river into avenues lined by thick vegetation. They deserved a second look with a tempting dry fly…

I was now in the water, eyes straining, waist deep on the tips of my toes, trying to see the fish that Nicholas was eagerly pointing at. It was at least 12 yards away from me under a leafy willow branch that was being constantly tugged downstream by the current. I could not see it at all. Was there something wrong with my glasses? Eventually I had to listen to his verbal instructions and cast the fly to within 6 inches of the target.

Second cast. Bang! The Yellow Humpy vanished into the swirling depths and my fish was on. Nicholas won the spotting competition hands down that day. Fourteen fish succumbed to my Humpy dry fly and Hare’s Ear nymph and well over half were fish that I could not see. This was sight fishing all right - but the guide’s sight, not mine. Many of the fish averaged 2 - 3lbs but the 1lb fish proved to be the most hard fighting and acrobatic fish I had ever caught.

Despite their exertions they shot off with renewed energy on their release. How different from the stocked fish of Southern England that require tender care and lengthy resuscitation before their release. No intensive care or oxygen masks needed for their Latin cousins - these are truly wild, fit and healthy fish.

Following a typical Argentine lunch of fine food and red wine, a 2-hour siesta was scheduled before returning to the river at 4.30pm. There’s no limit to your fishing time here - dinner isn’t until 10.30pm - so let’s fish till it’s dark! What a great way to spend a day.

The next day was not so idyllic. The wind struck up and white clouds rolled across the blue sky. I knew the day before was too good to be true. Nicholas was unperturbed. We sped off upstream in the boat and to my excitement, we found one of those fishy channels I had spied the day before. With a river is so large and diverse, whatever the weather it seems that you can still cast a fly - and catch a fish.

The channel turned out to be as productive as it looked. As we drifted quietly down the Amazon-like passage we occasionally heard heavy splashes under the overhanging shrubs and trees. Tell-tale ripples in the water guided us towards the spot, and 8 out of 10 times an accurate cast with a Stimulator hooked a fish. We were counting and laughing hysterically each time a plump brown trout hooked itself as it voraciously snapped at the fly. Maybe my spotting was not up to scratch but I took pride in not losing my fly in the overhanging branches - accurate side casting was the only way to achieve results.

As it turned out I was only at El Encuentro for two days. I want to return as I had only covered a tiny area of what’s available. Michael tells me that they have access to a Spring Creek and also take clients fishing in the nearby National Park.

I was in South America primarily to attend my brother’s wedding in Quito, Ecuador. Forty family and friends cruising round the Galapagos Islands on his new business venture, a cruise boat called The Eclipse, followed the event. It was an amazing experience with an educational emphasis on the cruise.

Four guides with science degrees enlightened us on, among other things, the theory of evolution. As I landed very sandy, light coloured brown trout that inhabited shallow sandy-bottomed water and silvery blue rainbows from the deep, dark blue waters I came to the conclusion that Darwin had a good point.

I have fished in America, New Zealand, and Alaska where, like Argentina, waters are open to all. Even though I thought I was going to the remotest areas in those countries, I still stumbled across other anglers. The Futaleufu is a long way from Buenos Aires and there are many other famous fishing areas in-between. The interest and pressure has not arrived yet at El Encuentro - but it will.

Maybe I should not be writing about this secret, but it would be a shame not to share it with a relatively small number of anglers who might go there for a few days. Michael has been there for over twenty years and wants it to remain the same for the next twenty years for his children. They are the future guardians and they need to make a living; it is a sustainable resource but a delicate one. As plans go ahead for one or two new lodges to be opened in the area, now is the time to enjoy this unique and unspoilt water with a family who know it and love it.

Oh and by the way, if after experiencing fishing at El Encuentro you end up on the Kennet with me, you won’t need any help in spotting those fish. Unless of course there is something wrong with your glasses…

For information on rates and how to get to El Encuentro contact Great Takes Travel at www.greattakestravel.com or info@greattakestravel.com. Lines are open weekdays on 0870 241 6990.