Makalu Base Camp, Nepal

The trek to the base of the fifth highest mountain in the world leads from dense rain forests over steep passes, to high pastures below glacier-clad peaks. Although only 125 miles long, the trek is tough as it involves an ascent of more than 7,000 metres and remote and rugged terrain. Once over the 4,100-metre Shipton La (pass), the route descends into the spectacular Barun river valley and climbs to the tongue of the Barun glacier, below the great dark wedge of Makalu.As the only way to get back is over the Shipton La, there is a degree of commitment not required on many treks. There are few villages and teahouses, making this even more of a wilderness trek. It passes through every climatic zone, from tropical forest to tundra and is a wonderful way to experience the huge range of environments found in Nepal.
• Twelve-day guided trek (14 nights total) with KE Adventure in October or November, £2,445pp full-board

Mountain crests, Corsica

The Grand Randonnée 20 (GR20) is a walk for those with a good head for heights who are happy scrambling over steep rocks for hours and days at a time. This spectacular route runs along the spine of Corsica, following the crest of the mountains. The crux of the route is the descent into – and climb out of – the great rock bowl of the Cirque de la Solitude. Here, chains and a ladder are bolted to the rock in places to aid progress.It’s not a place to slip. The GR20 is 112 miles long but takes most walkers at least two weeks, because of the steep, rocky terrain.
• Two-week guided trek with KE Adventure, departing weekly 3 July and 4 September, £1,595pp full-board

Cross the Arctic Circle, Sweden

In Lapland, in the far north of Sweden, a 280-mile footpath crosses the Arctic Circle and runs through four national parks and the largest nature reserve in Europe. This is the Kungsleden – the King’s Way – and it is magnificent. Starting at Hemavan in the south, the route runs through pristine pine and birch forests and Arctic tundra before finishing at Abisko, on the shores of Torneträsk lake. There are lodges along the way, run by the Swedish Tourist Association, although camping is necessary on some nights – which I recommend anyway. Long lakes are crossed by ferries run by local people, or by rowing boat. Glacier-clad mountains line the route, including the highest in Sweden: 2,097-metre Kebnekaise. The latter can be climbed on an extra trip. It’s an interesting ascent and the views from the summit are tremendous.
• Eight-day self-guided walk with Macs Adventure, £425pp including some meals and telephone support

After the watershed, Scotland

Running for 745 miles from Peel Fell in the Cheviot Hills, to the north-east tip of Scotland at Duncansby Head, the Scottish Watershed (between the Atlantic Ocean and the North Sea) is a twisting, tortuous route. It averages 450 metres in height and crosses many summits, including 44 munros (hills above 914 metres) and 24 corbetts (between 762 and 914 metres). There’s no path and the way is not always as obvious as you’d expect, so good navigation skills are essential. The Watershed doesn’t run in anything like a straight line and, at times, you can be heading south even though you are following it northwards.The terrain is also a challenge, often rough and boggy, sometimes dense with trees, sometimes steep and rocky.There are few buildings on or near the Watershed. It’s surprisingly remote and lonely but also a superb walk.
• ribbonofwildness.co.uk

High and remote, Pyrenees

Several trails run along the mountains from the Atlantic to the Mediterranean. Of these, the Haute Randonnée Pyrénéenne (HRP) is the most remote and challenging as it stays high in the mountains, crossing many passes and climbing several summits. The border between France and Spain runs along the crest of the Pyrenees and the HRP crosses it many times. It is about 500 miles long and takes around six weeks to complete. T as the route isn’t fixed and many variations are possible. There is a path much of the way but the route isn’t often waymarked and the terrain is steep and rocky. Mountain huts are sometimes several days apart, so camping is a necessity – and a boon as there are many lovely spots to pitch in. The HRP passes through many landscapes: some lush and green, some alpine, some almost desert.
• Guided HRP walk with Mountain Bug gives the option of tackling the trail in three one-week stages, departing 30 July, 6 Aug and 13 Aug, from £710 full-board

The Pacific Northwest Trail, US

Far less well known, and much newer than the Appalachian or Pacific Crest Trails, the Pacific Northwest Trail (PNT) runs 1,200 miles from the Continental Divide to the Pacific Ocean. Starting in the Rocky Mountains in Montana, it crosses the remote, little-visited Purcell and Selkirk mountains and the Kettle River range, before traversing the arid sagebrush country of the Okanogan and climbing into the North Cascades. Then comes a coastal and island section around Puget Sound before the final mountains of the Olympic range and a finish along the spectacular Pacific coast to Cape Alava, the westernmost point in the contiguous 48 states. Three national parks are crossed – Glacier, North Cascades and Olympic – plus several designated wilderness areas, including the vast and beautiful Pasayten Wilderness. The PNT is a challenging route with few waymarks and often no clear trail.
• pnt.org

The Arizona Trail, US

The desert terrain of the US south-west is a tough but rewarding place for walkers. One glorious trail runs some 810 miles, through the heart of Arizona from Mexico to Utah. En route, the Arizona Trail passes through deserts, canyons, forests and mountains. In the southern part of the state are the “sky islands”: small, steep forested mountain ranges that soar above the desert. These then fade into the flat, hot Sonoran desert (take plenty of water) before the trail climbs into two more extensive mountain ranges – the Mazatzals and the Superstitions. These mountains all have a touch of the desert about them.This changes in the northern part of Arizona as the vast Ponderosa pine forests of the Colorado Plateau are crossed, but before that, there is the highlight of the trail, the awe-inspiring Grand Canyon.
• aztrail.org

Great Divide Trail, Canada

Running some 745 miles through the southern half of the Canadian Rockies, from Waterton Lakes near the US border to Kakwa provincial park in northern Alberta, the Great Divide Trail (GDT) is a wilderness mountain route that closely parallels the watershed between the Atlantic and Pacific Oceans. It takes in five national parks – Waterton Lakes, Banff, Kootenay, Yoho and Jasper – along with four designated wilderness areas and seven provincial parks. The scenery is spectacular and wildlife includes grizzly bears, wolves, moose and mountain goats. The trail isn’t waymarked and there are some sections with no trail at all – much of the route is in remote country and there are few settlements. There are steep ascents and descents and streams that have to be forded. This is not a trail for novices, but the rewards for the effort required are great.
• greatdividetrail.com

Land’s End to John O’Groats, UK

Walking from the south-west corner of Britain to the north-east is a wonderful way to see the huge variety of scenery found in our small island. The many people walking and cycling it for charity every year mostly stick to the roads though. To really experience the splendour of this walk you need to follow footpaths and tracks. Many long-distance paths can be linked to create a splendid walk. The South-West Coast Path (with a diversion to Dartmoor if you tire of the coast), the Quantock Way, Offa’s Dyke, the Pennine Way, the West Highland Way, the Great Glen Way, and the Cape Wrath Trail can all be followed in full or in part. There’s no set route, so you can vary it as much as you like. The total distance is around 1,250 miles but maybe you want to take in the Lake District or the Cairngorms and add to that.
• landsendjohnogroats.info

Continental Divide Trail, US

Stretching 3,000-plus miles from Canada to Mexico, this trail follows the watershed of the US along the Rocky Mountains. In Wyoming it reaches the Parting of the Waters, where Two Ocean Creek splits, one branch starting a 3,500-mile journey to the Atlantic, the other a 1,350-mile journey to the Pacific. The CDT runs through much remote mountain and desert wilderness and is a challenging walk. It’s not fully complete yet and there are cross-country sections as well as old trails and dirt roads. Signposts are rare. The trail runs through many varied landscapes – the imposing peaks of the Northern Rockies in Montana and Idaho, the thermal geysers and hot springs of Yellowstone national park, the flat desert of the Great Divide Basin in Wyoming, splendid peaks again on the highest section of the walk in the Colorado Rockies, and finally the deserts and semi-deserts of New Mexico.
• continentaldividetrail.org

Chris Townsend has spent over four decades as a long-distance walker. His latest book, Out There, is published by Sandstone Press, £8.99. To buy a copy for £7.19 including UK p&p visit theguardianbookshop.com or call 0330 333 6846