If you are looking to get off the beaten track and take a trek that borders on an adventure then head to Western Nepal. The far west was historically little more than a gateway or stopping point for pilgrims heading into Tibet and onward to Mount Kailash. That has changed with the newly opened trekking region of Limi Valley which is attracting trekkers for a unique combination of isolation, rugged mountain landscapes and cultural authenticity. It's a restricted area but trekking permits cost on the order of $50 a week much cheaper than the $500 charged in neighboring Dolpo and Mustang. Trekking here can definitely be considered off the beaten track and whatever trekking infrastructure exists is primitive at best. All trekking parties should be self supported and go with a knowledgeable local guide. However, those managing the logistics will be rewarded with an incredible experience.
Western Nepal lies in the rain shadow of Dhaulagiri so the monsoon is relatively light. Snows frequently block passes in the winter so that the best time to trek is from late May to late October. Access to the region is via Nepalganj. Its the largest town in western Nepal and the first stop from Kathmandu. Flights to the more remote airstrips and trekking access points depart from Nepalganj to Simikot (for the Limi Valley Trek), Jumla and Dunai (Both Dolpo Region). Nepalganj at just 160m is relatively hot and being just 6km from the India border is strongly influenced by the cultural of Utter Pradesh. The town is rapidly developing and now hosts several decent hotels. A walk through the old bazaar should not be missed.
The most likely trekking destination here is the newly opened 20 day Limi Valley Trek. The highlight of the trek might be the ancient fortified villages of Janh, Halji but the remote wilderness feel and the mountain scenery cannot be overlooked. The trek itself passes crosses two high passes; Nara La (4580m) and Nyalu La (4990m). The trek starts in Simikot which requires a flight from Kathmandu and then onward to Nepalganj and Simikot. Another possible adventure for those who cant get enough and don't mind roughing it might be what is possibly a month long trek to the base camp of Api Himal. Api, Nampa and Saipal are a string of peaks located in the far west of Nepal and at over 7000m are the tallest peaks in this portion of the Himalaya.