Gomukh, also known as "Gaumukh" or "Gomukhi" is the terminus or pout of the Gangotri Glacier and the source of the Bhagirathi River, one of the primary headstreams of the Ganges River. The place is situated at a height of 13,200 ft in Uttarkashi district in the state of Uttarakhand, India. It is one of the largest in the Himalayas with an estimated volume of over 27 cubic kilometers. It is a holy Hindu pilgrimage site, along with Gangotri, as well as a trekking destination.
The word "Gomukh/Gaumukh" means "Mouth of a Cow." Before the heavy rains in the year 2016, the opening of the cave looked exactly like the "Mouth of a Cow."
The first and foremost thing for Gomukh trek is that you must have permission from (D.F.O.) District forest officer, Uttarkashi. Only 150 permits are issued per day. The trail to Gomukh begins from Gangotri, about 18 km (11.2 mi) from Gomukh. It was heavily damaged by rockslides by the 2013 North Indian floods as was road access to Gangotri. 9 km ahead of Gangotri is Chirbasa, the abode of Chir trees. After 3 km of Chirbasa comes the dangerous Gila Pahar, the place well known for its Landslides even prior to the 2013 destruction of much of the trail here; near-sheer cliffs down to the river must now be traversed. Here the Bharals, a type of mountain antelope are sometimes seen. The Bharals are found above the altitude of 10,000 ft. Only 4 km from here is Bhujbasa, the only night halting-place on the way with buildings. One can stay at the GMVN Bungalow, or at the Lalbaba's Ashram or at Ram Baba's ashram; both ashram charge Rs 350 for a day that includes lodging and food. After trekking 41/2km from Bhujbasa, one reaches Gomukh, the snout of the Gangotri glacier. A little before Gomukh, the majestic view of Mount Shivling welcomes the trekkers to the place. On the trail no horses are allowed, so one must make preparations to walk on foot. The trek to Tapovan and Nandanvan starts from here.
The route after 'Bhojbasa' can be quite difficult, more so since the 2013 floods. One has to cross a boulder zone to reach the Gomukh snout. The trek beyond Gomukh is quite difficult. Crossing the glacier & going towards Tapovan has become quite dangerous nowadays (because of the landslides). There is no track and one must have a guide and should be prepared to face any type of accident which can even be a life-threatening one. The last climb to reach Tapovan is very stiff, within 2 km a climb of around 1500 foot and is quite a challenging experience.
You may apply for an online permit at http://www.swsuttarkashi.com/Home/DashBoard, even with an online permit you would still need to get it verified at the district magistrate Uttarkashi office.