This is the most difficult and the longest trek [18days] which is considered to be one of the most difficult trek in the world, and it requires not only excellent health but also a high spirit of adventure. It starts off taking the same routs as Laya Trek. After reaching Laya .it turns eastwards and crosses the Ganglakarchung pass at 5.100meters[16730feet]into Lunana region where habitation is concentrated in the villages of Thega and Chezo, It is most difficult region of Bhutan to reach ,lying at 4,000m[13,000feet]The inhabitants are farmer-herder who are famous for their difficult Character, The trek then heads south and after crossing the Rinchenzoe pass, at 5220meters [17,125] it hits the tarmac at the Nikkarchhu bridge.