Anglers are a superstitious breed and none more so than fly-fishers. They have their little rituals. They have their lucky socks. They also have taboos, and uttering the “W” word is one of them. Mention the wind in a fishing lodge, its strength, its direction, its lack, and you’ll get looks as sharp as if your ringtone from Verdi’s Macbeth went off in a performance of The Cherry Orchard. At Kau Tapen lodge, however, where the untrammelled zephyrs of the South Atlantic make the flues of the wood‑burning stove clang like cracked wind-chimes, such taboos are pointless.

Kau Tapen is on the Argentine side of the island of Tierra del Fuego, south of the Strait of Magellan (windy) and just north of Cape Horn (windier). It takes such shelter as it can below a ridge above the valley of the Río Grande. It is just as far south as Blackpool is north, but the only time a bikini is to be seen at Kau Tapen is in the lodge’s sauna. It is two weeks past midsummer, and I am wearing two thermal layers, a down waistcoat, a wind-stopping fleece, two pairs of leggings and two pairs of socks below rain jacket and waders. I’m even wearing two hats, and I feel a little over-dressed, until I step outdoors. It is 4ºC. There is fresh snow on the Chilean hills. I now understand why the characters in Bruce Chatwin’s book In Patagonia all have red hands.

I had left beautiful Buenos Aires in a heat wave and landed in the two-horse town of Río Grande, where the raindrops ran horizontally across the cabin window. Why? Why becomes apparent as we drive away from the lodge, over the ridge where condors hang, and see the Río Grande itself, winding across a gravel plain marked with the scars of old meanders. There is a thrilling bleakness in this landscape and the river holds the largest sea trout in the world. Kau Tapen has access to a 20-mile stretch of it. A herd of guanacos canters along a camel-brown ridge as we drive down to the first pool.

I’m fishing with guide Agustín Garcia Bastons on a pool called “Morita’s” and using a single-handed rod. The wind is not so bad closer to the river, but it is still strong enough to put my casting technique to the test, until I start working with it. The wind is a stern examiner; it is also the sea trout-fisherman’s friend – it ruffles the water and makes fish that are normally spooky in daylight more inclined to take a fly, like the one that takes mine half way down the pool. It is only small – around 3lbs – which is lucky, because as I am playing it, my reel detaches from my rod and falls into the water. My tackle has failed its first test.

At lunchtime Jean-Baptiste Vidal, head guide, tries to fix the reel, but what with the aperitif, the wine, the exceptional meal – and the prospect of a siesta – I forget I have a care in the world, until he tells me the superglue hasn’t held as I am putting on my waders for the evening session. Timo, a self-confessed Swedish gear freak, lends me a truly slick reel from his home country, a Danielsson. (I neglect to ask him how it works.) Timo and his fishing partner Peter have 11 rods strapped to the front of their Subaru. Only one of them is Peter’s.

The sea trout in Tierra del Fuego may take well during the day, but they take even better during the magic hour before darkness falls. It seems like a long time to wait as a heavy shower passes over, but as I work through the slow section near the tail of the “Dos Equis” pool, José, my pair, shouts from upstream in the middle of the water. Agustín runs for the net. Writhing inside is a tremendous fish. It weighs 18lbs.

The wind drops with the fading light and we arrive quietly at “Condor”, our last pool of the day. There is enough light to find the length of cast and to see where the line lands in the reflection of the western sky. Something pulls at my fly and I back up a few steps. It doesn’t come again, but as I move down to where the fly fishes the seam between the current and the slack water I have a very solid take. It hits with a deep clunk. It is big. I realise I don’t know how the drag works on this reel, so I put my hand down to cup it, but the Danielsson’s revolutionary design doesn’t work like that either; there is no spool turning that I can slow with my palm. It is dark and I don’t know how much line has been taken. I also have no way of stopping this fish. And then it stops by itself and I start reeling and reeling, and then I’m reeling up slack line. It was big, but it has gone.

In the morning I put aside my fear that I have lost the biggest fish I will touch all week, and head downstream with guide Max Mamaev to “Boca”, the lowest beat on Kau Tapen’s water. Amazingly, there is not a breath of wind and the vast sky is scattered with popcorn clouds. Too bright, too still, says Max, but in the streamy run above “Boca” I hook a beautiful 8lb trout on a Sunray Shadow. In the still air, small butterflies flutter among the tufted grasses.

I had traded in the Danielsson for one of the lodge’s reels and continued with my single-handed rod – when the river is low it is easy enough to cover with a shorter rod. In fact, a small rod is essential on the evening we fish the Menendez, a tributary of the Río Grande. Jean-Baptiste is the right guide for this water; his technical, active style of fishing might seem fussy on a big pool, but here his directions help get my fly down to the bottom in the strange currents of “Japanise”, where I have two takes and I lose both fish.

There’s a pair of Norwegian anglers in the lodge, Helge and Leif, and Leif is going to be top rod for the week, landing fish after fish with rods that Helge’s company, 2instincts, makes. Helge has one he can lend me and it transforms the rest of my trip, a 12½-foot double-handed rod that sends a shooting head line far across “Hill’s”, and my fly into the path of a fresh 9lb fish. I’m in love. As the wind picks up again in the evening, José is fencing with it in “Big Horn”, where getting the fly tight to the far bank is important, while my sabre cuts through to land my first fish in the teens.

The next day the wind is back and stronger than ever, but the tables are turned. Guide Pelle Tronde takes us to where he thinks we can get a line out and José is better equipped to punch out a short line with his short rod. Pelle points me to a spot round the corner, a small run that is seldom fished, where the wind direction would not be so difficult. The Sunray Shadow again provokes a take, a fat 12lb trout that I beach on the shingle. It’s a long way off the best of the week – 24lbs for Kau Tapen, 32lbs for the river – but it is my most satisfying catch.

Often the wind drops towards dusk, but today it is getting stronger. We come to the last pool of the day and a gale is blowing straight down it. It is hard to open the door of the SUV. We lean into the wind to walk. Wading out at the top of the pool there are white caps breaking against my backside. But I am warm and dry, my line is zinging out, and the fly is fishing very well. After 40 minutes, José has had enough and gets back in the Subaru, but I am fishing the best sea trout river in the world at the perfect time of day with a guide so determined I get a fish that he stands upstream to act as a windbreak and changes my fly for progressively heavier Black Leeches. I am not stopping until something takes. And a willing seven‑pounder obliges.

We have Agustín again on the last evening. Near the middle of “Flamingo” is a smooth, green bank that curves down towards the water like the cushion on a snooker table and my fly – a rubber-legged nymph – bounces off it into the water. It swings round into the current, and is taken by a handsome fish that flick-flacks across the pool. Three casts later I land its twin. As the sun sets, Agustín takes us to where Timo caught the 24-pounder, but I cannot hook another fish to match the one I lost.  

In the twilight, the world appears stratified: a band of shingle, a strip of water, a ribbon of bank, a dado of horizon, a ceiling of cloud above and just where the bank touches the horizon, the gleam of light grows steadily into a rising moon, huge, two days off full. Upland geese honk on a gravel bar. Fish splash unseen. The sea trout are running.