From the south end of the Kullu Valley, the Tirthan Valley leads up southeast into the region known as Inner Seraj. This is an area of exceptional valley and mountain scenery, unspoiled villages and nature, great walks and inviting guesthouses. It's becoming known among Indians seeking a low-key escape from the plains, but is still off most foreign visitors' radar.
The Tirthan Valley is the gateway to the spectacular, World Heritage–listed Great Himalayan National Park, 754 pristine square kilometres of steep-sided river valleys and mountains reaching right up to the 6000m-plus peaks of the Great Himalayan Range.
Infact, a part of the Tirthan Wildlife sanctuary also is a World Heritage Site. This national park is home to the snow leopard & rare pheasants like the Western Tragopan. However the only way to see the core zone of the park is by foot. It takes 4-5 hours from Goshaini in Tirthan to reach the gates of the park at Kharongcha. The park offer several treks right from Shilt Thatch to Rakhundi peak & sainj Valley on the right side, to Hanskund & Nada Thatch if you go straight & to Khorli Poi & Asur Baag on the left hand side, all a part of the Tirthan Wildlife Sanctuary- a part of the World Heritage Site.