Into the wide open?

Hard trek
Located in the north-western tip of India, the state of Arunachal Pradesh, covers a tremendous amount of terrain, not much smaller than the whole of Nepal. The former contained more than 40 hot springs so it's not surprising to see that Arunachal Pradesh has quite some thermal activity, though possibly less developed and / or visited. It's therefore understandable that there's less info on the internet available.

Re-known for the many different ethnicities, Arunachal Pradesh is distinctly remote, little roads offer any kind of access. Tawang district bordering both Tibet and Bhutan is accessible and contains largely Tibetan Buddhist ethnicities. As one of the most accessible mountain areas it's not surprising to find that (as is the case with Bhutan to it's east) there are a number of hot springs not far away from Tawang itself (relatively speaking ...).

Tsachu Hot Spring is a bit of a language anomaly; Tsachu already being the Bhutanese name for a hot spring. It seems to be the most well-known, though not so easy to visit:

'Tsachu hot spring which can be reached by traveling by a light motor vehicle for two hours from Tawang up to Sarong Gonpa and trekking from there for another three hours'.

Or:

'Tsachu Hot Spring can be reached by travelling for 4 hours by a vehicle and another 4 hours on foot'.

Do note that Tawang is 10 hours drive from the nearest airport .... Tripadvisor is still waiting for reviews ... And this website notes the distance from Tawang as 230 km and adds:

'Apart from hot spring, this site is also suitable for hard trekking'.

The hot spring of Thingbu is located 68 km away from Tawang town. Apparently a pony is the most used form of transport for the final stretch from the roadhead.

Other hot springs located in Tawang district are Kitpi or Greng-khar (Grenkhar), the former being the name of the village rather than the name of the hot spring. This website adds:

'It is about 40 kms away from tawang town.This hot water spring and ‘ Manchu’ provides warm, sulphur rich water and cures many ailments'.

There's a slightly scientific entry on hot springs in Tamang which hardly adds to the above other than this gem:

'Monpa, Sherdukpen, Miji and Aka tribes take holy bath in these hot springs in the belief that their sins will get washed away. They also take a dip in the water for 1–3 h for healing any kind of skin disease.

Dejection
Mago hot spring is located nearer Jang:

'where the water is so hot that “yak meat is cooked in 20 minutes”'.

Despite the above being the most well-known(?) in Arunachal Pradesh, there are no first hand experiences shared. This contrasts with Dirang (West Kameng district, south of Tawang), famous for it's apples, kiwi's and yaks to which Roy Biswas has paid a visit:

'The other famed tourist spot is the Hot Water Spring, which is also the main attraction for locals, who supposedly take bath in the Hot Springs as its water is said to possess curative properties. However, I was most dejected after having undertaken a long trek down from the main road, as an Ecological Camp has come up at the site, with a Cafeteria right in front of the Hot Spring, which is not only blocks the view of the Hot Spring, but also creates more ecological hazards, rather than preserving the ecology there for which it is meant & sounds. The local environment department needs to take a look at this, before it gets too late to redeem the hot spring'.

Others chime in:

'We had the exact same reaction when we went to check out that hot spring at Dirang. I would have expected at least a little bit of improvement there from 8 years back'.

Lower Dirang valley contains a hot spring near the village of Jia.

Located just inside of the Arunachal Pradesh - Assam border, the western town of Bhalukpong has it's own hot spring:

'Bhalukpong, which lies about 85 kilometers away from Bomdila on the foothills of Aka ranges, is an ideal picnic spot. The picturesque site is also a home to the Jia-Bharali river and a hot spring, which is believed to have a medicinal value (source)'.

Hot spring (sanaser, May 2014) 

Bomdilla. Source.

More to the east, Anjaw district contains two hot springs, one named Walong circle, the other Kibithoo circle.

'Located 20 km away from the Chinese border, Walong is situated on the western bank of river Lohit in Anjaw district. The mesmerizing place is famous for its hot water spring and the Namti valley. The hot spring is located amazingly at the confluence of river Dichu and Lohit. It is a major attraction of Walong and tourists fly to the place to take a soothing bath in the medicinal water of the hot spring'.

Source

As always when there is little reference material, some caution is required as often different names as used for the soak!

Soaking with six of the seven sisters

Nestled among the Himalaya itself and the surrounding mountains lie the so-called seven sister states of Northeast India.

Way back in January 2010, Arunachal Pradesh, the most mountainous sister, had been highlighted but the remaining six states warrant some soaking attention.

Soaking for elephants. Not.

The biggest and least mountainous state, Assam has no less than 2 Garampani's; places which denote a spring of hot water. Most mentioned is the hot spring located in Nambar Forest Reserve, but exactly which Garampani it is, is unclear. In 2010 this website gave this information:

'... the two more famous ones [hot springs] are located in Golaghat district and North Cachar Hills. The one in Golaghat district is located in the Nambar Reserve Forest about 19 km southwest of Golaghat town. The water of this spring contains hydrogen sulphide and its temperature is 53⁰C to 58⁰C'.

Let's call this the Nambar Garampani. Other striking info on Nambar comes from this website:

'Elephants have now been denied the right to drink water out of Mother Nature’s very own hot spring in the wilderness of Assam. The Garampani hot spring by the side of National Highway 39 in Karbi Anglong district, Nambor Reserve forest, is now guarded by a huge ugly concrete wall. The area is an elephant corridor which the jumbos use almost on a regular basis'.

Looking more intently at the photo of this spring it seems that the wall is just for safety reasons with elephants as well as humans being protected for their own good. Sad though, that the elephants can no longer soak. 

A video of Garampani.

Underwater
Then aforementioned citation (from 2010) concludes that there is another Garampani hot spring in Assam state near the

'... headstream of Kapili is at a distance of 33 km east of Jowai. Its water is 35⁰C warm'.

Let's say the Kapili hot spring or Kopili as I have seen or Umrangshu (Umrongso?), an often used alt. This Garampani is located close to the border with Meghalaya state in an area known for tea plantations and the hydro project on the Kapili. This website mentions:

'The beautiful Umrongso Lake, the quite valley, the hot water springs and the exquisite scenery are enough to captivate attention. The visitors in this area can enjoy both hot and cold bath and fishing in the river Kopili'.

It's unclear to me whether this hot spring still exists. Here I read

'7-km away from Umrangshu in Meghalaya , the hot spring Garampani is lost in the water of Kapili Hydro-Electric Project. Barrage and dams are constructed on the Kapli River along 19-km area from Umrangshu to Hot Spring. A Lake has already come up over here'.

Wikipedia finally mentions that the hot spring is

'now lost'.

More sisters
In reality there is little info on hot springs in the North-eastern states of India.  Tripura and Mizoram seem to contain no hot springs. 
For Nagaland I found one mention of Tangkum Marok but am unsure whether or not this spring is hot.
Manipur contains Ukhrul saline springs. This link mentions:

'The Saline Springs of Ukhrul are the Salt springs of Ukhrul located in the outskirts of the town.

Ukhrul has a number of brine wells located at Chingai, Challao, Nameri, Luchai-Khullen, Mariem and Kharawam. The water from these springsis used in making salt cakes'.

Again uncertainty remains about the supposed heat of the springs at hand.
 
That leaves us with world's wettest region, the state of Meghalaya.
By far the most often mentioned in Meghalaya is the hot spring of Jakrem (Lawblei). Unfortunately most mentions are as follows:

'Jakrem in Meghalaya is fast gaining popularity among tourists as it is a wonderful health resort. It is blessed with hot-springs of sulphur water which lure people from across the globe. It is believed that the water of the hot springs is endowed with curative medicinal properties. People come here to bathe in these hot-springs for good health'.

From photo's of Jakrem one can only conclude that the claim that it lures people from all over the world seems a little hollow, though the surroundings are appealing.

From the Megha hot spring resort website.

The state Department of Tourism adds:

'Jakrem has now developed as a potential health resort. People from all parts of the region throng here to take a dip in the hot spring. Bathing compartments are available around the spring for the use of the public. It is also a favourite picnic spot during winter'.

The Shillong Times notes (December 8, 2013) that a bacteria was found here which was previously uncharacterised.


Elsewhere there are only lesser known hot springs in Meghalaya such as the hot spring of Umngi which is situated along a trekking route:

'Weiloi to Ponkung / Pongkung to Umngi: One can reach Weiloi village from Shillong by car / bus. On the way from Weiloi to Umngi there exist two natural mineral water springs. The Hot Spring of Umngi has the potential for becoming a health resort'.

Possibly 2 hot springs?

Resubelpara is the name of a town in north of Meghalaya which possibly moonlights under the name of Williamnagar. Some 15 kms away (from Williamnagar) is apparently a hot spring by the name of Bakra (source). There's even a small photo album on Facebook.

[updated August 2014]