My trip started from Dehradun to Tapovan and back with 48 kms of trek and 400 kms of motorcycle ride all in 5 days. Dehradun to Gangotri is 200 kms approx and I was pretty acquainted with the route as the place had always been a dear destination for me for weekends. Perks of living in a place so close by.
1) Gangotri to Bhojwasa (12 kms)
2) Bhojwasa to Tapovan and back to Bhojwasa (18 kms)
3) Bhojwasa to Gangotri (12 kms)
How to reach Gangotri
1) Plenty of public transport like buses and taxis are available from Haridwar, Rishikesh and Dehradun. All these cities can be arrived at by trains too.
2) One can drive to Gangotri in his personal vehicle, car or a motorcycle, or hire a self driven car. Roads are neat with minor broken sections. Roads after Uttarkashi to Gangotri (90 kms) are narrow which needs caution.
Permits for Gaumukh trek is mandatory and are easily available before 12:30 am for trekking on the same day. Since the trek is long its advisable to get the permits early or a day before. Too late and they wont give you one. Also the permits for Gaumukh Tapovan trek a has a certain cap for one day. They allow only a limited number of people per day. So its better to go early or day before. Your IDs are required and a minimal fee is charged.
Things to Check
1) Plastics: After permits you are finally checked at the forest check post 1-2 kms into the Gaumukh trail. All your luggage is checked for unwanted items like plastics. Its advisable to go with less plastics as possible. Chips, disposables, plastics bags, mugs, plastic cans etc will be charged and noted down and the charged money will not be refunded if you don't come with the items you went with. I ended up bringing more plastic than I took. Collected the ones lying around.
2) Navigator : Going beyond Gaumukh taking a navigator is compulsory. As the trek gets precarious after crossing Gaumukh a navigator is mandatory and will be charged extra. You will have to search for one in Gangotri itself the day before and it will be included in your permit. The check post wont allow you to go further if you are wishing to go beyond Gaumukh without a navigator.
3) Medicines : "Essential medications" are subjective to take but recommended as the conditions change quite often at these altitudes. Headache, stomach illness, nose bleeding, skin itches and burns due to UV rays, high altitude sickness and shortness of breath are some common problems I have seen among people. Carry essential medicines, sun blocks and SPFs and don't just pop a Diamox in at high altitudes. Be responsible and do a good homework and research before you go.
4) Clothes : A good warm jacket which can tolerate low temperatures. A set of thermal inner wears. Spare loose pants (trekking in denims is not recommended). Good shoes. Probably a hat to cover your face and neck from sun burns.
5) Luggage : Be a minimalist and pragmatic and keep your luggage as small as possible. Bigger the luggage more the effort you will have to put in to walk the trek. Even a few extra grams bother a lot over such treks and high altitude walks.
1) Chirbasa : A very very small settlement with only 3-4 people to accommodate for the night. Not recommended. The place serves as a spot for snacks and few supplies to get you going.
2) Bhojwasa : The only major settlement. Cheapest option is to stay at Lal Baba Ashram. Accommodation charges are 350 per person which includes bed, dinner, breakfast and lunch for a whole day. GMVN rooms are also available.
3) Tapovan : Mauni Baba Ashram is the only place to stay here. One needs to depart early from Bhojwasa to secure a place here too. Slightly costly a 700 per person with amenities similar to Bhojwasa.
High mountains make their own weather. Warm clothing a raincoats are advisable. It gets very cold at night and it rains only for a short while as it turns into snow.
The route is very demanding physically. If you don't wish to walk you can take a mule ride from Gangotri to Gaumukh. Mules don't go beyond Gaumukh. The route from Gangotri to Gaumukh has lot of water crossings too. Good shoes are necessary and spare socks too. The trek gets difficult after Gaumukh to Tapovan. While you move ahead from Gaumukh to Tapovan you will navigate the galcier. Navigating the Gaumukh glacier is where the navigators come in handy. The final ascent after Crossing Gaumukh glacier to Tapovan is very steep and precarious.
I could talk about this for hours. Since it was the best and worst I had.