These 10 classic treks are for serious walkers. All of them require a sturdy pair of lungs, fit legs and a good amount of preparation. However, all of these trails offer experiences that last a lifetime. In no particular order:
1. GR20, France
This demanding, 15-day (168km) slog through Corsica is legendary for the diversity of landscapes it traverses. There are forests, granite moonscapes, windswept craters, glacial lakes, torrents, peat bogs, snow-capped peaks, plains and névés (stretches of ice formed from snow). But it does not come easy: the path is rocky and sometimes steep, and includes rickety bridges and slippery rock faces - all part of the fun. Created in 1972, the GR20 links Calenzana, in the Balagne, with Conca, north of Porto Vecchio.
2. Inca Trail, Peru
This 33km ancient trail was laid by the Incas and is currently traversed by thousands each year. The trail leads from the Sacred Valley to Machu Picchu winding its way up and down and around the mountains, taking three high passes en route. Views of white-tipped mountains and high cloud forest combine with the magic of walking from one cliff-hugging ruin to the next - understandably making this South America's most famous trail.
3. Pays Dogon, Mali
"The land of the Dogon people" is one of Africa's most breathtaking regions. A trek here can last anywhere between two and 10 days, and takes in the soaring cliffs of the Bandiagara escarpment inlaid with old abandoned cliff dwellings. Dogon villages dot the cliffs and are an extraordinary highlight of the journey. The Dogon are known for their masked stilt dancers, intricately carved doors and pueblo-like dwellings built into the side of the escarpment.
4. Everest Base Camp, Nepal
Reaching a height of 5,545m at Kala Pattar, this three-week trek is extremely popular with those who want to be able to say, "I've been to the base of the world's highest mountain". The difficult trek passes undeniably spectacular scenery and is trafficked by Sherpa people of the Solu Khumbu. The heights reached during this trek are literally dizzying until you acclimatise to the altitude, and the continuous cutting across valleys certainly has its ups and downs.
5. Indian Himalayas, India
Fewer folk trek on the Indian side of the world's greatest mountain range. So, if isolation is your thing, try trekking in Himachal Pradesh. Hardcore hikers can try teetering along the mountain tops for 24 days from Spiti to Ladakh. This extremely remote and challenging walk follows ancient trade routes. The bleak high-altitude desert terrain inspired Rudyard Kipling to exclaim, "Surely the gods live here; this is no place for men".
6. Overland Track, Australia
Tasmania's prehistoric-looking wilderness is most accessible on the 80km, five- to six-day Overland Track. Snaking its way between Cradle Mountain and Lake St Clair (Australia's deepest natural freshwater lake), the well-defined path (boardwalked in parts) passes craggy mountains, beautiful lakes, extensive forests and moorlands. Those who want more can take numerous side walks leading to waterfalls, valleys and still more summits including Mt Ossa (1,617m), Tassie's highest.
7. Routeburn Track, New Zealand
See the stunning subalpine scenery of New Zealand's South Island surrounding this medium three-day (32km) track. At the base of New Zealand's Southern Alps, the track passes through two national parks: Fiordland and Mt Aspiring. Highlights include the views from Harris Saddle and atop Conical Hill, from where you can see waves breaking on the distant beach. The main challenge for this popular hike is actually securing a place among the limited numbers who are allowed on the track at any time.
8. The Narrows, United States
A 16-mile journey through dramatic canyons carved over centuries by the Virgin River, the Narrows in Zion National Park is a hike like no other. The route is the river, with more than half of the hike spent wading and sometimes swimming. The hike can be traversed in a day, though some choose to take the hanging gardens and natural springs at a more leisurely pace - spending a night at one of the park's 12 camp grounds.
9. The Haute Route, France-Switzerland
Leading from Chamonix in France through the southern Valais to Zermatt in Switzerland, the Haute Route traverses some of the highest and most scenic country accessible to walkers anywhere in the Alps. The summer Haute Route walk (which takes a different course than the more famous winter ski-touring route) takes around two weeks to complete. It mainly involves "pass hopping" and demands a high level of fitness, with every section containing a high huff factor.
10. Baltoro Glacier and K2, Pakistan
This corridor of ice leads to the colossal peak of K2 (8,611m), the world's second-highest peak. This incomparable trek traverses some of the most humbling scenery on the planet. What begins following icy rivers boldly goes to the guts of the glacier before leading to the granite pyramidal mountains including Paiju (6,610m), Uli Biaho (6,417m), Great Trango Tower (6,286m) and ultimately K2. If the 15 days does not floor you, take side trips to more moraine-covered glaciers.
Source: By Lonely Planet