My years of angling adventures began in the Himalayas in 1989, when the fishing world was full of secrets and mystery. My last journeys to Mongolia and Tibet took place a quarter of a century later when the internet had laid pretty much all of the angling world bare. In the 1990s my companions and I set off with hope in our hearts and little idea what was in store for us but knowing that if we got to our destination, we’d probably be the first foreigners to wet a line there. We plunged into the unknown world of hidden fishing, trusting to fate and what little information we could find from any possible source. (Read an Albanian fishing adventure.)

Today, though, the most far-flung waters are served by outfitters, guides, cosy-bedded lodges and superb kitchens. Every item of tackle or clothing that you might need you can now research and buy. Every method and technique you can check on You-Tube, so you arrive with all the veils of wonderment pulled aside. So, are there any expeditions you can mount today where the adventure remains intact and the internet hasn’t revealed all? Here’s my guide to hidden fishing.

Spain

Andalusian barbel on the fly

Where and why: Spain hardly sounds like a voyage into the unknown but the rivers that flow south from the mountains around Ronda into the Mediterranean between Gibraltar and Malaga are crystal, fast flowing and hold the fabulously coloured Andalusian barbel that can be stalked and fooled into taking a nymph or even a dry-fly. These are fish routinely between two and six pounds, so a 5wt floating line outfit will do. Keep mobile, expect to walk and wade, and enjoy the thrill of finding hidden valleys rich in golden orioles and wild figs.

Adventure score: 8/10. You’ll have to find your own beats along volatile, everchanging rivers and roads little travelled. Obtaining a licence isn’t easy and you’re on your own when it comes to fly choice.

Logistics: Fly to Malaga, head to Ronda and look for Benaoján Estacion, a village 10 miles out. There the super river Guadiaro can be fished for miles both north and south. For licences, visit: licenciasdecazaypesca.es

Cost: £ to ££ (£ symbol for each estimated £1000 you might spend)

Slovenia

Huchen

Where and why: The huchen, aka the Danube salmon, is a mighty sportfish barely known to UK anglers and that’s a tragedy because they are big, take flies and fight with all the ferocity of a 30-pound plus salmonid. The Sava River, close to Bled, is majestic, studded with glides and pools, and flows through gobsmacking Alpine scenery. Winter is the time to fish there, in the silence of the forests when the mountains are capped with snow.

Adventure score: 7/10. Because of the huchen’s rarity, I’m tempted to up the score but Slovenian anglers are a helpful lot and you’ll have assistance, notably from Rok Luštrik if you contact the greatest huchen guide of all.

Logistics: Fly to Ljubljana and the rivers are little more than an hour away. November to February is the window when it can be fridge cold.

Cost: ££

Swedish Lapland

Top-water pike fishing

Where and why: The far north of Sweden is all about water, not land. There are literally tens of thousands of lakes holding pike of serious size in considerable numbers. Surface fishing with floating patterns is the method for these predators and this is the perfect place. The water is clear, fishing pressure is light and it’s doubtful whether the pike you cast to have ever seen a fly. Pike here spawn in June, and by July are feeding hard in the shallows where a floating fly works best. Fish at midnight and watch the fly in the light of the sun as it still rolls on the horizon.

Adventure score: 5.5/10. While this trip takes you many miles from home into pristine wilderness for hidden fishing, you are still in civilised Sweden. Good outfitters with passionate guides are there for the booking.

Logistics: Be there as the pike begin to feed in July. Fly to Stockholm and then take interior flights to the region. The Arjeplog mountain range is a good place to begin research plus the tackle shop in that town is a mine of information.

Cost: ££/£££

Morocco

Fly-fishing in the Atlantic coast surf

Where and why: The Ksar Massa beach, south of Agadir, faces the Atlantic, which surges in with relentless power. Behind you stretches the wilderness of the Sahara but it’s the pounding surf you are fishing, with an 8wt for spotted bass, bream and jacks of every size and shape. Shrimp patterns are a safe bet, fished in the gullies where the tide churns and the fish forage. Takes are dynamic – even small fish pull your arm off. Look out for flamingos, spoonbills and perfect sunsets.

Adventure score: 7/10. This is a little known adventure and one you can fashion for yourself but the locals are obliging with advice and Agadir is easily reached. A safe, exhilarating trip.

Logistics: Fly to Agadir and check out hotels close to the shoreline. Obey local customs, especially relating to alcohol. The bigger fish arrive in June.

Cost: ££/£££

Sri Lanka

Golden barramundi and tuna

Where and why: Sri Lanka has been little fished by UK anglers since it became independent and shed its colonial name Ceylon. This is a shame. Sri Lanka is a beautiful island, the people warm and welcoming, and secret fly-fishing opportunities exist in profusion. Bolgoda Lake is a massive 144 square miles in extent, partly brackish and holds 45 species of fish, notably the great golden barramundi. Flyfishing for these warriors from a small boat can be spectacular, if you can take your eyes off the sea eagles and bank-side langurs. For an ocean adventure, drop down the coast to the enchanting town of Galle and head out with local boatmen for a wild tuna experience.

Adventure score: 8/10. The country is a wonderful tourist destination but much of the fishing has to be discovered personally. Local boatmen will take you afloat and part of the adventure lies in finding them.

Logistics: Fly to Colombo direct if you can (avoid transferring in Mumbai especially). Taxis to take you south from the capital are easily arranged. Avoid the hottest months.

Cost: ££/£££

Greenland

Arctic char

Where and why: The short west-coast rivers of Greenland are wild, rugged streams that can come straight from the ice cap. They host legions of stunningly coloured char that leave the sea and run the rivers to spawn in the summer months. These are big fish, up to 10 pounds and more, and they fight like demons in the ice-cold waters. All flies work but big surface patterns pulled back fast are hit hard.

Be prepared to walk distances to find the best pools, often beneath gushing waterfalls, and always keep an eye open for musk ox, which can be tricky customers.

Adventure score: 8.5/10. You can find outfitters, generally Danish, to help get you started, especially on the famed Kangia river, but you’ll still have to cope with the loneliness of this vast landscape.

Logistics: Fly to Kangerlussuaq, probably from Copenhagen. From there you will travel to the rivers by small plane, helicopter or boat. The best months are early July to mid-September. And prepare for mosquitoes.

Cost: £££

Mongolia

Taimen and Amur pike

Where and why: The immensity of this fabled land holds extraordinary fish, not least the great land-locked salmon, the taimen, and the Amur pike: the close relative of our own Esox lucius. Both species grow huge – the Amur to 60 pounds and the taimen to double that – and both can be caught on the fly. If these fish are amazing, so is this lonely, forbidding land nestled in the heart of Asia. I have suggested the Onon River in the east of the country, close to the Chinese border, because both pike and taimen can be found in this enormous water system. You’ve got to be tough. The fishing can be brutal and the living will be hard. It’s likely you will walk big distances or ride by horse. You’ll hear wolves at night under a sky dazzling with stars.

Adventure score: 9/10. I’m going high here because even if you go with an outfitter, the trip will be challenging. Don’t expect luxury and feather beds. There won’t be many Brits either, more likely rock-hard Czech anglers.

Logistics: Fly from London to Frankfurt and from there with MIAT to Ulaanbaatar. Then travel east by plane or helicopter, as roads are horrendous. British anglers can visit without visas and the best months are from August to late September – but not too late lest you are snowed in for the winter. Cost: £££/££££

The Amazon catchment

Arapaima

Where and why: The mighty Amazon and its tributaries are home to these extraordinary fish in Brazil, Bolivia, Ecuador, Peru, Colombia and Guyana, so in theory you have options. In practice, these leviathans are now scarce and are best targeted in pockets of protected water. Arapaima are massive: 400 pounds and with dazzling, blood-red tails. Prehistoric in looks, they take flies the size of swallows and fight with unbridled power. They have to be targeted when the Amazon is low and the fish are concentrated in shallow lagoons and side streams. They take in around 70% of their oxygen from the air, showing themselves on the surface every 15 minutes or so. Now is the time to get close, paddle near silently and make the perfect cast. Then watch that 12wt gear groan under pressure impossible to believe.

Adventure score: 9/10. Despite the appearance of lodges now, arapaima are rare, huge fish that are endlessly hard to find, difficult to fool and back-breaking to land.

Logistics: June to November is generally considered the time to go. Flights can be costly from the country’s capital and then away deep into the Amazonian rainforest.

Cost: £££/££££

Republic of Congo

Goliath tigerfish

Where and why: These are the ultimate predators living in the most frightening river on the planet. The Congo is an untamed force and these fish reflect their home to a horrifying degree. Goliaths are fish of huge size, huge strength, huge rarity and with huge teeth. Jeremy Wade regards them as the greatest trophy fish and the most dangerous to hunt: venomous snakes, tsetse flies, malarial mosquitoes, hippos and the threat of robbers. And that doesn’t include the massive problems of catching the beast.

Adventure score: 10/10. Even though there are now a handful of outfitters, this is a quest of extreme hazards.

Logistics: Fly into Brazzaville from the UK but spend a great deal of time beforehand talking to those outfitters and ensure you have your vaccinations for hepatitis A and B, cholera, typhoid and tetanus before you go.

Cost: £££/££££

Nagaland

Chocolate mahseer

Where and why: Nagaland is that mysterious territory south of Tibet, neighbouring Assam. Until recently it was partly closed to visitors but was always rumoured to hold the legendary chocolate mahseer. I co-led a party there in 1995 and there is still little information about fishing the area. All I can do is outline the logistics of what we did in the hope of inspiring some equally intrepid adventurers of today. From Kolkata, we flew to Dibrugarh in Assam before travelling a day or more by ferry on the Brahmaputra River. Upon landing, we drove two days across the border into Nagaland and followed the Siang gorge as far as the Yamne River where we made base camp. We were a week too late and the possible ‘chocolates’ had spawned and returned to the huge Siang where they were impossible to locate.

Adventure score: Off the chart. We saw wonderful things in this untouched world but we were arrested under suspicion of spying, suffered serious injuries in a jeep crash and had endless brushes with buffalo and big cats. Perhaps this is the ultimate hidden fishing that remains just as adventurous even in the modern age.

Cost: £££/££££