For many centuries, Bhutan was isolated from the rest of the world. It was only in the 1960’s that Bhutan first became connected to India by highway from Thimphu. Then in the 1980’s the first flights from India began arriving to Paro. The infrastructure of Bhutan has improved much over the last several decades. There is now a network of roads entering and traversing the country, as well as one international and multiple domestic airports within country. Because of its remoteness, Bhutan has no port or railway system.
Paro is the only international airport in Bhutan. Currently there are only two airlines that fly into Bhutan. You must book your flight with either Druk Air or Bhutan Airlines.
Druk Air offers more international and domestic routes for travelers. It operates daily flights from Bangkok (Thailand). It also flies two or three times per week from Dacca (Bangladesh), Kolkata, Bagdogra, Delhi, Bodh Gaya, Guwahati, Mumbai in India, Kathmandu in Nepal, and Singapore. (Please check the Druk Air website for the latest schedule).
Bhutan Airlines offers daily flights from Bangkok to Paro via Kolkata, India and three flights a week to Delhi via Kathmandu.
There are three port of entry and exit while travelling overland.
Phuentsholing, (border southwest commercial town), roads and railways networks are well established with other popularly tourist destination namely Darjeeling, Kalimpong & Indian state of Sikkim and rest of India. And it’s merely 4 hours drive to Bagdogra (nearest Indian airport). Jaigoan is the Indian border town where you have to exit Indian visa to enter Bhutan and vice versa.
Samdrup Jongkhar (far south east town). It share its border with Indian state of Assam. The nearest Indian Airport is at Gawahati, which takes approx 3 hours to reach Samdrup Jongkhar. It adjoins with small Indian border town called Daranga, which harbour Indian Immigration Checkpost for related Indian visa work.
Gelephu(Mid-south border town.). Which is 245 kms away from nearest Indian airport of Guwahati. Dathghari is the adjoining Indian border town, where all relevant Indian visa work are processed by the Indian Immigration Checkpost.
Please review the new procedures concerning the new Indian e Tourist visa on arrival. The new regulations have caused some confusion with travelers and can cause problems if not followed. More information can be found here: Single entry India E-Tourist Visa Vs Regular Visa