Har Ki Doon is a very popular place among trekkers. The best way to reach this place is from Mussoorie through Yamuna Bridge, Naugaon, Purola, Saur, Sankri, Taluka and Osla.Har Ki Doon has bungalows as well as rest houses for trekkers, located at an altitude of 3506 m. The trek passes through thick forests and mountainous surroundings. The Ruinsara Lake, located at a distance of eight kilometres from Osla is a major attraction.