Generally, Bhutan is travelled to by road, since it has only one functional Airport. The Druk Airways is the only carrier in Bhutan, and the ticket prices are on a steeper side.
The Paro International Airport is the only airport in Bhutan. It is located in the south west of the country and caters only to Druk Air with flights connecting Bangkok, Delhi, Kolkata, Bodhgaya, Bagdogra, Guwahati, Kathmandu and Dhaka to Bhutan. The fares are a little steep. However, it is also widely considered to be one of the toughest airports in the world to land at.
Bhutan can be reached by bus too. Buses are available from Kolkata and Siliguri to Phuentsholing. The ticket prices range from BTN 300 to 700.
There are no railways in Bhutan. However, if you are travelling from India, you can take a train to Hasimara which is 15 km from Jaigaon, the border town on the Indian side of the border (near Phuentsholing).
There are three land border crossings located along the southern border that is linked to India only. Phuentsholing, Gelephu and Samdrup Jongkhar. Road permits are required if you wish to get in by road. These permits can, however, be processed along with your visa.
There are no waterways in Bhutan.
Jaigaon is the Indian town touching Indo-Bhutan Border, and Phuentsholing is on the other side. All the formalities to get a permit to enter Bhutan, are carried out here at the immigration office.
One can take a flight till Bagdogra from anywhere in India. After landing in Bagdogra, hire a taxi to Jaigaon (Approximate fare - INR 2500). One can also take a bus to Jaigaon from Siliguri or Kolkata. It takes approximately four to five hours to reach Jaigaon from Bagdogra. You can easily walk from Jalgaon to Phuentsholing and back without a permit. Phuentsholing and Jaigaon offer an array of accommodation options for a break journey.
Another way to reach is to take a train from Siliguri to Hasimara junction which is accessible from Jaigaon via local transport (Rickshaw). The train takes approximately 2.5 hours to reach Hasimara from Siliguri.
The gate remains open from 8:00 AM IST to around 11:00 PM IST. The immigration office in Phuentsholing is only 100 m away from the gate.