Sikkim is a state in East India in the Himalayan foot hills also bordering China (Tibet), Nepal and Bhutan.The name has been coined from the words 'Su','Him'i.e. beautiful home.Though it should be better named by abode of nature.The snow covered mountains & lush green valleys not only invigorates one's soul,it also leaves the spectators bewildered by the extravaganza of its natural beauty. Nearly 40% of the total area is forested.
The state official language of Sikkim is Nepali, which is also the primary language of most locals. Many other languages such as Dzongkha and Tibetan are also spoken by smaller numbers. However, Hindi is also widely spoken as a second language, and all educated people are able to speak English.
There are no railway stations in Sikkim. The ways to enter Sikkim from rest of India is by road using bus or jeep from West Bengal, or by flight at Sikkim's only airport at Pakyong. Nearest Railway Station is New Jalpaiguri (West Bengal). One can reach Gangtok capital of Sikkim from New Jalpaiguri in 04 hours by taking a shared taxi or Individual Taxi.
As of April 2017, it is still necessary to obtain a Restricted Area Permit (also known as Inner Line Permit) for foreigners to travel in Sikkim. The permit is a piece of paper containing your passport data and dates you are permitted to travel (typically, 15 days). When entering and exiting Sikkim, your passport will be stamped much in the same manner as when crossing state borders. Obtaining a permit is a pure bureaucratic formality and usually takes a few minutes. You will need to fill in an application form and provide a few passport photos (1 and 2 have been reported).
The permit can be obtained when crossing the Sikkim state border by road in Rangpo or Kelli. It is also available from Sikkim permit desk in Darjeeling located at the District Magistrate office after first securing the stamped application form from the Foreigner Registration (FRO) office next to the clock tower, and from Sikkim Tourism Center in Siliguri located at the S.N.T. bus stand (the place from which government buses depart for Sikkim, S.N.T. means "Sikkim Nationalized Transport") in the vicinity of Siliguri Junction railway station (different from New Jalpaiguri station, and can be reached from there by taxi/public shared taxi), the area is known as Pradhan Nagar. The web-site of Ministry of Home affairs states that permits can also be obtained at large international airports (Delhi, Mumbai, Chennai, Kolkata), but locating the relevant facilities proved difficult due to incompetence of the personnel. Permits can also be applied for at the time of Indian visa application, or at 14 Panchsheel Marg, New Delhi 110021 (011 26115346) and 4/1 Middleton Street, Kolkata 700071 (033 22817905)
For rented bikes, you need to get permits for your vehicles and the driver/co-drivers from the Secretariat office in Gangtok. This office opens at 10 AM and closes by 4 PM. It takes around 3-5 hours to issue the permits from the time of application. You need to submit the bike rental agreement on a stamp paper along with the RC, insurance, Emission certificates of the vehicle. Plus the Passport size photo, ID & Address proofs of the drivers and pillions. On the application form, you need to mention the number of days of travel and the route that you will be taking. Submit these documents along with the application form that is available from nearby photocopy shops. The office will issue 4 copies of the permit letters. One of them is to be submitted to the Police permit office located near MG Marg. One is for your reference. And the remaining 2 copies are to be submitted at the police check posts at the entry and exit points. Make sure you make 3 photocopies of the permit letters which will be collected at the check posts.
The police permit office near MG Marg open at 5 AM and closes at 8 AM. You need to submit the permit letter along with the documents mentioned in the above paragraph with a passport size photo and application form. Once they issue the permit you are free to go.
So, basically, you will need to spend 2 days in Gangtok for the permits. First get the permits from the Secretariat office and the next day from the Police department.