If you aren’t coming from Kyūshū, then the best way to get in is by plane. Nagasaki Airport (NGS) is well served by main Japanese airports such as Chubu Int’l, Haneda Int’l in Tōkyō, Naha Airport and Itami Airport in Ōsaka. The duration of the flight is approximately 2 hours coming from Haneda and 70 minutes from Ōsaka.
From Nagasaki Airport the city center is easily reachable by bus.
If you wish to reach Nagasaki by train, the station to be considered is Hakata Station, in Fukuoka. (be careful when looking on timetables: Fukuoka’s main station is “Hakata” and not “Fukuoka” which is totally elsewhere)
From Hakata Station to Nagasaki there are two Limited Express services every hour and the trip is just shy of two hours. By using local lines only (i.e. if you are taking advantage of the Seishun 18 kippu), Nagasaki is reachable from Hakata in approximately 4 to 5 hours with a stopover (usually at Tosu station).
If you own a Japan Rail Pass, all of the aforementioned lines are covered by it (for the exception of the express trains Nozomi or Mizuho from Ōsaka), and we highly recommend the Japan Rail Pass Kyūshū(or the Ryugakusei pass Kyushu if you’re a student) if you wish to focus your attention on this island.
As many sights and attractions in Nagasaki are situated just south of the station, it is extremely easy to visit even just on foot. To reach the park and the atomic bomb memorial zone, however, it is necessary to burn a couple of miles. We recommend doing so by using the landmark Nagasaki tramways!