For international and domestic travellers who want to fly in, the closest international airport to Nainital is Indira Gandhi International airport (IGI) in New Delhi. There is one more airport in Pantnagar which is closer to Nanital 68Km approx 2 and half hours. There's an airport in Bareilly too which is only 3 hours from Nainital.
Regular Deluxe and Volvo bus service is available from Delhi. The price of the tickets is between Rs 300 and Rs. 700. One can also take a direct taxi from Delhi to Nainital which can cost anywhere up to Rs 8000 for a roundtrip.
The most convenient way to get to Nainital is to take a one of the several trains that run to/from Kathgodam(35km from Nainital)the closest railway station. Trains like Ranikhet Express from Jaisalmer, Garib Rath from Jammu, Luncknow and Kanpur, Naini Doon Jan Sampark from Dehradun, Bagh Express from Howrah, Shatabdi and Sampark Kranti from Delhi come to Kathgodam. One can take either a bus or a taxi to Nainital from there.
The drive to Nainital from Delhi takes about 6-8 hours. The scenic road trip offers beautiful views of the mountains and the plains below.