Sopot is part of Poland’s tri-city area in the north, and nestled right between Gdansk and Gdynia. The town is not very big and you can pretty much make it everywhere by foot, but if you are flying in, you’ll be coming from the Gdasnk Airport. The local commuter train (SKM) from Gdansk Glowny will take you to Central Sopot in less than 20 minutes. If you are coming from Gdynia, take the train from Gdynia Glowna to ul. Bohaterow Monte Cassino and Al. Niepodlegosci in Sopot, which should also take about 20 minutes as well.
Rarely will you find yourself needing a taxi as most of Sopot’s hotels are within walking distance to and from the major tourist attractions and beaches, but if you find yourself needing to take one from either Gdanski or Gdynia, it will run you about 30 to 50zl one way. If you are taking the bus though, Sopot does not have its own bus station, so you will need to either stop in Gdynia or Gdansk before taking a train or taxi and heading into Sopot.